The lengths of two sides of a triangle are 9 and 15. What can be said about the length of the third side?
A. It must be greater than or equal to 6 and less than 24.
B. It must be greater than or equal to 6 and at most 24.
C. It must be greater than 6 and less than 24.
D. It must be greater than 6 and at most 24.