I think the question is best described by an example:
You are at a doctors office and are about to have a conversation about you birth control prescription. Before you can enter you have to decide if you want the female doctor or the male doctor with you in the room. The decision is made on either a sheet of paper or screen listing the female and male doctors name with a checkbox attached.
Depending on which option is listed first or on top the decision is biased towards that option. If for example the male doctor is listed first the patient might feel that selecting the female doctor is out of the ordinary or 'extra work' just for her. The patient might be inclined to choose the first option to avoid any confrontation.
This might be especially true if the patient feels uncomfortable with the topic of the appointment.
In what form could we present the options as to not give any bias as to what the "normal" or expected answer is?