Create drop down product attribute in Magento 2

Today  I am going to explain, how we can create drop down attribute for Products in Magento 2.
There are two ways to create the drop down attribute in Magento.
1 -> Manually : Go To admin panel,  Store -> Attributes -> Product .
2 -> Programmatically .

In this blog I am covering how we can create the drop down attribute programmatically,
So let’s start :
Step 1 : create InstallData.php file : Company\Module\Setup\InstallData.php
Now In this file, create an Array of the attributes that you want to add as below.

$attributeGroup = 'Test Group';
        $attributes = [
            'attribute_code' => [
                'group'              => $attributeGroup,
                'input'              => 'select',
                'type'               => 'int',
                'label'              => 'Attribute Label',
                'visible'            => true,
                'required'           => false,
                'user_defined'               => true,
                'searchable'                 => false,
                'filterable'                 => false,
                'comparable'                 => false,
                'visible_on_front'           => false,
                'visible_in_advanced_search' => false,
                'is_html_allowed_on_front'   => false,
                'used_for_promo_rules'       => true,
                'source'                     => \Company\Module\Model\Config\Source\Options::class,
                'frontend_class'             => '',
                'global'                     =>  \Magento\Eav\Model\Entity\Attribute\ScopedAttributeInterface::SCOPE_GLOBAL,
                'unique'                     => false,
                'apply_to'                   => 'simple,grouped,configurable,downloadable,virtual,bundle'
            ],...
          ];

Step 2 : Now Add and Assign Attribute to Group and Attribute Set.

// Add Attribute
// Magento\Eav\Setup\EavSetupFactory  $this->eavSetupFactory
// Magento\Framework\Setup\ModuleDataSetupInterface $setup

 $eavSetup = $this->eavSetupFactory->create(['setup' => $setup]);
            foreach ($attributes as $attribute_code => $attributeOptions) {
                $eavSetup->addAttribute(
                    \Magento\Catalog\Model\Product::ENTITY,
                    $attribute_code,
                    $attributeOptions
                );
            }
//Assign 
            foreach ($attributes as $attribute_code => $attributeOptions) {

                // Class \Magento\Eav\Model\AttributeManagement

                $this->attributeManagement->assign(
                    'catalog_product',
                    $attributeSet->getId(),
                    $groupId,
                    $attribute_code,
                    $attributeSet->getCollection()->getSize() * 10
                );
            }

Note :
$attributeSet : you can load the attribute collection and loop for it or Can pass specific id instead.
$groupId : Magento\Eav\Model\Entity\Attribute\Group : you can get the group id with the help of this class.

Now , Options for drop down attribute , you can add options directly as a array.
and another approach is to use class Magento\Eav\Model\Entity\Attribute\Source\AbstractSource  as follows :

<?php

namespace Company\Module\Model\Config\Source;

class Options extends \Magento\Eav\Model\Entity\Attribute\Source\AbstractSource
{
    /**
    * Get all options
    *
    * @return array
    */
    public function getAllOptions()
    {
        $this->_options = [
                ['label' => __('No'), 'value'=>'0'],
                ['label' => __('Yes'), 'value'=>'1'],
                ['label' => __('Other'), 'value'=>'2']
            ];

    return $this->_options;

    }

}

Please read each line carefully, so that you can create the attributes easily.
and In case you have any Query then feel free to ask in comment section below.