Choose the alternative that completes the series: SHG, RIF, QJE, PKD, ?

Concept

In a letter series made of equal-length groups, examine each letter position as an independent alphabetical sequence. Convert letters to alphabet positions when useful, identify the step in each column, and apply every step to the latest group.

A valid next term must continue all column-wise movements simultaneously.

Application

1. The first letters S, R, Q, P move backward by one place each time; the letter after P in this descending pattern is O.

2. The second letters H, I, J, K move forward by one place each time; the next letter is L.

3. The third letters G, F, E, D move backward by one place each time; the next letter is C.

4. Combining the three independently obtained letters gives OLC.

Cross-check

Using alphabet positions, the groups are (19, 8, 7), (18, 9, 6), (17, 10, 5), and (16, 11, 4). Each transition is (−1, +1, −1), so the next group is (15, 12, 3), which maps to OLC.

Therefore, the missing term is OLC.