Which of the Following A/B Tests Would Most Likely Be

Which of the following A/B tests would most likely be unethical?

A) If Facebook uses different shades of green in its interface to measure users' responses.
B) If users are incited to act out against immigrants.
C) If users are incited to purchase additional amounts of product.
D) If Facebook redirects visitors to a page programmed to display variations of a sales pitch.