According to the graph, during which time interval are the particles in the air slowing down?
A. 3:00 p.m. to 6:00 p.m.
B. 6:00 p.m. to 12:00 a.m.
C. 3:00 a.m. to 6:00 a.m.
D. 6:00 a.m. to 12:00 p.m.

