Subject: mathqa
Question: a store has 10 bottles of juice , including 5 bottles of apple juice . in the evening , 6 bottles of juice are sold one by one . what is the probability of selling 3 bottles of apple juice among the 6 bottles ? assume that every bottle has an equal chance of being bought .
Option: 
A: 4 / 9
B: 8 / 15
C: 10 / 21
D: 12 / 25
Answer: C