The given sequence is: Z, Z, Y, Y, Y, X, X, X, X, W, W, W, W, V W, ......., A

So, the number of terms in the given sequence = $2 + 3 + 4 + \dots + 27 = [\frac{27 (27 + 1)}{2}] – 1 = [\frac{27 \times 28}{2}] – 1 = 378 – 1 = 377$

So, the middle term is $378/2$, i.e. 189th

Now, $377 – (27 + 26 + 25 + 24 + 23 + 22 + 21 + 20) = 189$

So, the 189th term must be I.

Hence, option (B) is correct.