निम्न अक्षर शृंखला में अगला पर क्या है? ACBD, FHGI, KMLN, ?

Each group takes letters at positions n, n+2, n+1, n+3: ACBD (1,3,2,4), FHGI (6,8,7,9), KMLN (11,13,12,14). Each group starts 5 letters later, so the next starts at P (16): P, R, Q, S = PRQS.