An Advantage of Using a Panel of Consumers for Marketing

An advantage of using a panel of consumers for marketing research is

A) the discussion leader can help change negative panel responses into positive ones.
B) the company can find out if consumers change their purchasing behavior over time.
C) panel members often help each other by bringing up ideas for discussion that others didn't initially think of but that were important to them.
D) there will usually be one panel member who dominates the discussion and helps keep the conversation focused.
E) panel members are highly defined demographically, so it is relatively simple to replace an individual member without losing continuity.