A school with 60 teachers is on alert during a nighttime storm. To inform teachers whether the school will open the next day, the principal will call four teachers, each of whom will call two others, and each of these will call two others, and so on until all 60 teachers have been contacted. How many teachers will have to make two calls?

A) 32
B) 29
C) 16
D) 24
E) 28