From the given options select the one which complete the series:

Y, ?, ?, M, I, E

U,Q

The following table shows the position values of the alphabets:

Answer will be UQ

We can also memorize the alphabets so that we do not do any calculation mistakes and also reduce the time to solve answers: 

We know, the values of respective letters from the above table:

Y = 25, U = 21, Q = 17, M = 13, I = 9, E = 5

Instead of dealing with alphabets we convert it into number to make visibility of the pattern easy:

As, we know 21 stands for "U" and 17 stands for "Q" that means answer is UQ.

When we see the series alphabetically, we often get confused. Converting them into number series will reduce the time and effort for the same, with minimum calculation error.