Mrs. Jones teaches in room 121. There are 20 students in her first period science class, and 30 students in her second period science class. When is the density of people in the room highest? a. During first period, because there are fewer people in the room.
b. During first period, because there are more empty desks in the room.
c. During second period, because there are more people in the room.
d. During second period, because it is later in the day.​