Statement (1) doesn’t give us any information about the number of blue marbles at all. It is not
sufficient and we can cross off A and D.
Statement (2) doesn’t give us any information about the number of red marbles, so we can
eliminate B.
When we combine both statements, we have ratios that involve all three colors of marbles. Let’s
see what happens when we use some real numbers. If there are 6 green marbles, then there are
4 red marbles and 5 blue marbles, making the ratio of red to blue marbles 4:5. If we used a different
number for the green marbles - say, 12 - we would end up with the same ratio of red to blue.
This happens frequently with relative numbers such as ratios, proportions, averages, and probability;
keep in mind that you don’t always have to know the actual numbers to know the ratios.
Statements (1) and (2) together are sufficient, so the answer is C.