I will go with A
1. Since there are twice as many white balls as black balls.
Probability to extract a white ball will be 2/3
2. "If two balls are extracted from the bowl, the probability that both of them are black is 0"
This is only possible when either there is no black ball or either 1 black ball. So we cannot determine the probability of extracting a white ball...
Am I correct ?
Yup sporty. Just one clearification.
I assume that sufficiency of A is pretty clear.
As far as B is concern, black ball cant not be 0 since question states that
A bowl contains white and black balls
So it is clear that there is 1 black ball.
Why B is insufficient?
assume there are only 1 black and 1 white ball- probability to extract a white ball from the bowl= 1/2
Now assume there are 3 white balls and 1 black ball - probability to extract a white ball from the bowl is 3/4
B is insufficient. Answer is A.