Use the graph below to answer the question that follows:

cosine graph with points at 0, negative 1 and pi over 2, 3, and pi, negative 1

What are the amplitude, period, and midline of the function?
A) Amplitude: 4; period: π; midline: y = 1
B) Amplitude: 4; period: 2π; midline: y = 5
C) Amplitude: 2; period: 2π; midline: y = 5
D) Amplitude: 2; period: π; midline: y = 1