Observe the separate letter-wise pattern according to its position in the given series.
1st letters: B, F, ?, O, T ⇒ Letters positioned at 2, 6, __, 15, 20 i.e. with difference of 4, 5, 4, 5, .., so letter at postion 11=K
2nd letters: G, K, ? , S, W ⇒ Letters positioned at 7, 11, __, 19, 23 i.e. with difference of 4, so letter at position 15=O
3rd letters: F, J, ? , R, V ⇒ Letters positioned at 6, 10, __, 18, 22 i.e. with difference of 4, so letter at position 14=N
4th letters: Z, U, ?, K, F ⇒ Letters positioned at 26, 21, __, 11, 6 i.e. with difference of 5 in reverse order, so letter at position 16=P
.'. Required cluster of lettrs is KONP
Correct Option 8)