A principal is organizing a field trip for more than 300 students. She has already arranged the transportation for 220 students. Each school bus has the capacity to transport 40 students. Which of the following inequalities could be used to solve for x, the number of school buses still needed to transport all of the students?
A. 40x - 220 > 300
B. 40x + 220 > 300
C. 40x > 520
D. 40x > 300