There are 25 balls in a jar. You take out 5 blue balls without putting them back inside, and now the probability of pulling out a blue ball is 1/5. How many blue balls were there in the beginning?
Choose the correct choice from the following answers:
A) 12 .  B) 9 .  C) 8 .  D) 7 .  E) 6 .

Rationale: "9 = 5 blue balls + 20 / 5 answer : b"
Answer: B