Which of the Following Is True Regarding Conscious Parallelism

Multiple Choice

Which of the following is true regarding conscious parallelism?

A) Proof,standing alone,that firms changed prices at the same time is sufficient to prove a horizontal conspiracy to set prices regardless of whether the firms initially set prices at the same levels.
B) Proof,standing alone,that firms initially set prices at the same levels is sufficient to prove a horizontal conspiracy to set prices regardless of whether the firms later changed prices at the same time.
C) Showing that firms consistently set prices at the same levels and change prices at the same time is sufficient to prove a horizontal conspiracy to set prices.
D) Merely showing that firms consistently set prices at the same levels and change prices at the same time is insufficient to prove a horizontal conspiracy to set prices.