Probability = Number of outcomes / Total number of possible outcomes.
So, using this formula we can get our answer
To get total number of possible outcomes we have to add all the marbles
i.e. 16 + 15 + 12 + 7 = 50
And now plugging it in the formula
Probability (drawing a green marbles) = 16/50
= 8/25
So, Correct option is C.
Hope this helps you... :D