[ish]

Thanks Brinda
oops sorry.i meant 2/3. i saw that it was the last but one choice and put in D.
this is how its 2/3


There are two identical bottles. One bottle contains 2 green balls and 1 red ball. The other contains 2 red balls. A bottle is selected at random and a single ball is drawn. What is the probability that the ball is red?

you can choose a red ball by choosing the first bottle OR the second one. The prob for choosing a bottle is 1/2. Say we choose the first one.
choosing a red ball from that one is 1/3, so the total prob for the first bottle is (1/2)(1/3)
suppose I choose the second bottle. Prob for doin that is 1/2 as well. Choosing a red one from the second one is done in 2/2 ways. Total prob is (1/2)(2/2)
Add them up, 1/6 + 1/2 is 2/3.