result.html

<select id="membership_id" name="membership[id]"><option value="IG">Inspector General (CO) (LTC)</option>
<option value="IG">Inspector General (CO) (LTC)</option>
<option value="NU2013">Class of 2013 (STU)</option></select

weird.rb

array = [
#<Membership user_id: 1160, group_id: "IG", role_id: "CO">,
#<Membership user_id: 1160, group_id: "IG", role_id: "LTC">,
#<Membership user_id: 1160, group_id: "NU2013", role_id: "STU">
]


html << content_tag("li") do
  groups = array.map do |member|
    ["#{member.group.name} (#{m.role.id})", m.group.id]
  end
  select("membership, "id", groups)
end