An Effective Sampling Program Meets Three Criteria

An effective sampling program meets three criteria. Which of these is NOT one of them?

A) The purchase cycle should be short enough that the consumer will consider an immediate purchase.
B) The brand being sampled must be a packaged good such as food or health care products.
C) A small sample must be able to adequately demonstrate the product's core features and benefits.
D) The cost of the sample being provided should be relatively low.