A series is given with one term missing. Select the correct alternative from the given ones that will complete the series.
I, M, ?, U, Y

Let's look at the numerical positions of the given letters:
I=9

M=13

U=21

Y=25

The difference between consecutive known terms is:
13−9=4
25−21=4

Following this uniform addition of +4:

Missing term=13+4=17⟹Q
Verifying the next step: 17+4=21 (U), which matches.