Please,could you help me understand what is wrong with wrong answer which I gave.

A bag contains & red marbles, 7 white marbles, and 9 blue marbles. You draw 4 marbles out at without replacement. What is the probability that all the marbles are red? 8 7 5 The probability that all the marbles are red is 21 21 12 What is the probability that exactly two of the marbles are red? 5 7 16 The probability that exactly two of the marbles are red is 21 23 22 What is the probability that none of the marbles are red? 16 15 11 13 The probability of picking no red marbles is 24 23 Submit Question 9 acer 96 5 7 B