the answer is C. what you do is since Maria had already picked a marble out t you would add up the blue, red, and green marbles (subtracting the green she had already taken out) so that's 15. and then you take the 6 red marbles and make a fraction. 6/15. the fraction would be the red marbles over the total marbles left. then you could then simplify the fraction by dividing it by 3 and that leaves you with C 2/5