Answer:
Option B
Explanation:
1st Number : $1+4\rightarrow 5, 5+4\rightarrow 9, 9+4\rightarrow 13, 13+4\rightarrow 17$
2nd letter : $C+3\rightarrow F, F+3\rightarrow I, I+3\rightarrow L, L+3\rightarrow O$
3rd letter : $V-1\rightarrow U, U-1\rightarrow T, T-1\rightarrow S, S-1\rightarrow R$
Thus the term 15LS is wrong andmust be replaced by 13LS
Hence the answer is (b).