One Thousand Adults Live in Milltown

One thousand adults live in Milltown.All of them leave work at 4:30 p.m.every day and arrive home at exactly 5:00.They all go to bed at 9 p.m.Three fundraisers,Alpha,Beta,and Charlie,have targeted Milltown's population.Because the charities raising the funds are identical,the first to call a willing donor will get the donation.
Refer to the information given above.Calls made by fundraisers at each firm will tend to:

A) be evenly distributed throughout the evening.
B) cluster near 5:00 p.m.
C) cluster near 6:00 p.m.
D) cluster near 7:00 p.m.