Multiple choice general knowledge math & puzzles A,D,I,P W X Y S Reveal answer Fill a bubble to check yourself C Correct answer Explanation The series corresponds to the squares of integers: A=1 (1^2), D=4 (2^2), I=9 (3^2), P=16 (4^2). The next term is 5^2 = 25. The 25th letter of the alphabet is Y.