Answer: A:16 marbles
Step-by-step explanation:
Because the number of blue marbles has to be four times as many as the number of green marbles, the blue marbles have to be a multiple of 4 because the number of marbles has to be a whole number.
Look at the options to see any option that is a multiple of 4.
That option is 16 so option A is correct.
Blue marbles being 16 means that green marbles are 4.
