Three of these four letter groups are built in the same way. Which one is built differently? EGIK, JLNQ, MOQS, PRTV

Write the alphabet positions. EGIK is 5, 7, 9, 11; MOQS is 13, 15, 17, 19; PRTV is 16, 18, 20, 22 — each of these steps up by 2, 2, 2. But JLNQ is 10, 12, 14, 17, whose steps are 2, 2, 3, so the last letter should have been P, not Q. The trap is checking only the first two letters of each group, where all four look identical.