Concept:The relation is found by subtracting consecutive numbers from the letter positions.Explanation:Take J=10, K=11, L=12, M=13.Subtract 1,2,3,4 respectively:10−1=9→I11−2=9→I12−3=9→I13−4=9→ISo, JKLM:IIII.Now apply the same rule to P=16, Q=17, R=18, S=19.16−1=15→O17−2=15→O18−3=15→O19−4=15→OThus, the result is OOOO.