select_tag + options_for_select

select_tag "credit_card", options_for_select([ "VISA", "MasterCard" ], "MasterCard")
# => <select id="credit_card" name="credit_card"><option>VISA</option>
#    <option selected="selected">MasterCard</option></select>

select_tag + options_from_collection_for_select

select_tag "people", options_from_collection_for_select(@people, "id", "name")
# <select id="people" name="people"><option value="1">David</option></select>