Answer: 5/18 is the correct answer.
Step-by-step explanation: The top number of your fraction is the total amount of green marbles which is 5. The bottom number of your fraction is 18 which is the total of all the marbles added together. 6+4+3+5=18. Since the fraction can not simply, you have your answer of 5/18. The answer was also confirmed on the test I took. I hope this helps you! Thanks!