A. The relation is not a function because each input has the same output.
B. The relation is not a function because each input should have a unique output.
C. The relation is not a function because each input has exactly one output.
D. The relation is a function because each input has the same output.

There are 20 blue marbles and 30 other than blue marbles.

Probability of drawing blue marble is 20/50 = 0.40

Probability of drawing other than blue marble is 30/50 = 0.60

Using the Binomial theorem, The probability of exactly 2 blue ball out of 5 is given by

5C2 0.40^2 0.60 ^3

= 10 * 0.40^2 * 0.60^3

= 10 * 0.16 * 0.216

= 0.3456

= 36% approx