select_tag default value & options

#If you are using select_tag without any other helper, then you can do it in html:

select_tag "whatever", "<option>VISA</option><option selected=\"selected\">MasterCard</option>"

#Or with options_for_select:

select_tag "whatever", options_for_select([ "VISA", "MasterCard" ], "MasterCard")

#Or with options_from_collection_for_select:

select_tag "people", options_from_collection_for_select(@people, 'id', 'name', '1')

#Examples are from select_tag doc, options_for_select doc and from options_from_collection_for_select doc.