Five search options always have drop-down menus. They are Business State, Business Country, Residential State, Residential Country, and Occupation. Other search options that may have drop-down menus are Degrees Earned and Job Title.
You will know a drop-down menu is available because you will not be able to type in the edit box. Click the triangle next to the edit box to make the drop-down menu appear. Scroll through the list and select the criterion you wish to search. Click Enter, and then click Find Now.