Of the Following Situations, Which Would Be the Most Appropriate

Of the following situations, which would be the most appropriate for using a discontinuous/omnibus panel?

A) To gain insights into changes in consumers' purchases and attitudes
B) To determine if members of the panel switched brands from one time period to the next
C) To determine how consumers feel about two different product packages by varying panel questions from one panel measurement to the next
D) To have a focus group moderator ask participants about their views on a new advertisement.
E) All of the above.