The given series BCYX, EFVU, HISR, KLPO follows a pattern where each term is formed by taking the first letter of the previous term, moving two positions forward in the alphabet, then taking the second letter of the previous term, moving one position forward in the alphabet, then taking the third letter of the previous term, moving two positions backward in the alphabet, and finally taking the fourth letter of the previous term, moving one position backward in the alphabet.

Applying this pattern, the next term in the series should have the first letter as "N" (moving two positions forward from "K"), the second letter as "O" (moving one position forward from "L"), the third letter as "M" (moving two positions backward from "P"), and the fourth letter as "L" (moving one position backward from "O").

Out of the given options, option 1 "NOML" is the correct answer because it follows the pattern mentioned above.

Note: It is important to carefully analyze and apply the pattern to each option before selecting the correct answer.