The fifth term of the alphabet series BCYX, EFVU, HISR, KLPO, ? is
First letter: B, E, H, K, …
The positions in the alphabet are B=2, E=5, H=8, K=11.
The difference between consecutive terms is 5-2=3, 8-5=3, 11-8=3. The pattern is +3.
The next first letter is K + 3 positions = 11 + 3 = 14th letter, which is N.
Second letter: C, F, I, L, …
The positions in the alphabet are C=3, F=6, I=9, L=12.
The difference is 6-3=3, 9-6=3, 12-9=3. The pattern is +3.
The next second letter is L + 3 positions = 12 + 3 = 15th letter, which is O.
Third letter: Y, V, S, P, …
The positions in the alphabet are Y=25, V=22, S=19, P=16.
The difference is 22-25=-3, 19-22=-3, 16-19=-3. The pattern is -3.
The next third letter is P – 3 positions = 16 – 3 = 13th letter, which is M.
Fourth letter: X, U, R, O, …
The positions in the alphabet are X=24, U=21, R=18, O=15.
The difference is 21-24=-3, 18-21=-3, 15-18=-3. The pattern is -3.
The next fourth letter is O – 3 positions = 15 – 3 = 12th letter, which is L.
Combining the next letters, the fifth term of the series is NOML.