I honestly went by elimination so
Work:
Teacher = 4 Â Student = 2
A) 5 Teachers = 20 pizza   1 Student = 2   = 22
B) 4 Teachers= 16 Pizza    2 Student = 4   = 20
C) 3 Teachers = 12 Pizza   3 Student = 6    = 18
D) 2 Teachers = 8 Pizza  4 Student = 8    = 16
E) 1 Teacher = 4 Pizza   5 Student= 10   = 14
Answer
There are exactly 3 Teachers and 3 Students. Â (Answer C)