The correct option is B 2:1
Take LCM of sum of d ratios and consider it as the total amount (of course the total amount will be the multiple of sum of ratio, but then this way you get your answer faster)
Here, the sum of the individual ratios are 9(4+5) and 6(2+3+1)
LCM of 9 and 6 = 54. (You can LCM or multiply numbers for fast result. If you take LCM it would give 18).
So, considering 54 as the total amount,
I st case, A's share was 24 abd B's share was 30
2 nd case A's share = 18
B's share = 27
C's share = 9
Thus, A's share reduces by 24 - 18 = 6
B's share reduces to 30 - 27 = 3
Ratio = 6:3 = 2:1