The correct option is A 1
L(X) = Number of a's and number of b's is multiple of 3Now let's see the strings,1: a32(ba)128 na=32+128 =160 (Which is not divisible by 3)So this string does not belongs to L(X).2: a2017b2018a2019 na= 2017+2019 = 4036(Which is also not divisible by 3)So this string does not belongs to L(X).3: (a72b14)2 na = 72×2 =144 (Which is divisible by 3) nb = 14×2 = 28(Which is not divisible by 3)So this string does not belongs to L(X).4: ∈32 na= 0 (Which is divisible by 3) nb = 0 (Which is divisible by 3)So this string belongs to L(X).So only 1 string belongs to the L(X).