In how many ways can a dance committee of 15 students be chosen, consisting of exactly 4 juniors, 3 seniors, and the rest being freshmen or sophomores, from a group of 6 freshmen, 6 sophomores, 5 juniors, and 6 seniors? 
 
A) 315 ways 
B) 420 ways 
C) 525 ways 
D) 630 ways