Since a and b are in the ratio 2:3,the first and 2nd terms of an answer must be in the same ratio.
We see that it occurs in option (a) Where 10:15=2:3
But there , a:b:c=10:15:33
Therefore , in that ratio,
a:c must be 10:33 or b:c must be 15:33=5:11 to verify the answer (a)
if a:c is not 10:33 or b:c is not 5:11 then none of the options verify the answer.
Ans) The answer is (a) if and only if a:c=10:33 or b:c=5:11