Shopify Display Multiple Variant Drop-down on Collection Page

display-variants-dropdown-shopify-collection.liquid

<form action="/cart/add" method="post" style="text-align:center;">
  <select name="id">
  {% for variant in product.variants %}
    {% if variant.available %}
    <option value="{{ variant.id }}">{{ variant.title }} - {{ variant.price | money }}</option>
    {% else %}
    <option disabled="disabled">{{ variant.title }} - Sold Out</option>
    {% endif %}
  {% endfor %}
  </select>
  <input type="submit" value="Buy now" />
</form>