Students from a school participated in a field trip, for which two buses were hired. When the buses arrived, 57 students entered the first bus and only 31 in the second. How many students should transfer from the first to the second bus so that the same number of students are transported in both buses?
(a) 8
(b) 13
(c) 16
(d) 26
(e) 31
The correct option is (b).

The total number of students in the two buses is $57+31=88$ and $\frac{1}{2} 88=44$. For each bus to have the same number of students, $57-44=13$ students must move from the first bus to the second bus.