圭塘站
赤岗岭站
Please solve the multiple choice problem and put your answer (one of ABCD) in one "\boxed{}". According to the subway map, how many intermediate stops are there between 圭塘站 and 赤岗岭站 (except for this two stops)? 
A) 15 
B) 18 
C) 21 
D) 1 
