The given series is BCYX, EFVU, HISR, KLPO, ?. To find the missing term, let`s analyze the pattern in the given series.

In the first term, BCYX, if we consider the positions of the letters in the English alphabet, we can observe that the second letter, C, is two positions ahead of A, the first letter. Similarly, the third letter, Y, is two positions ahead of W, and the fourth letter, X, is two positions ahead of V.

In the second term, EFVU, following the same pattern, we can see that F is two positions ahead of D, V is two positions ahead of T, and U is two positions ahead of S.

This pattern continues throughout the series, where each letter in the term is two positions ahead of the corresponding letter in the previous term.

Using this pattern, the missing term should start with the letters M and O, followed by two letters backward in the English alphabet. Looking at the options, we can see that option 1, NOML, satisfies this pattern.

Hence, the correct answer is option 1, NOML.