What Is the General Rule for Selecting a Marketing Research

What is the general rule for selecting a marketing research supplier?

A) Choose the least expensive supplier and,if the project's needs exceed their abilities,move to the next supplier.
B) Choose the smallest firm consistent with the scope of the project,as long as the project is not more than 30% of the supplier's annual revenues.
C) Choose the vendor that has the best reputation.
D) Choose the smallest firm consistent with the scope of the project,as long as the project is not more than 15% of the supplier's annual revenues.
E) There is no general rule.