Choose the letter of the best answer. Write the chosen letter on a separate sheet of paper. 1. What is the greatest common factor of 18 and 36? A. 4 B. 6 C.18 D. 7 2. Which of these numbers are the common prime factors of 14 and 56? A. 2, 7 B. 3, 7 C. 7, 14 D. 4, 7 3. Which number is the greatest common factor of 16 and 24? A. 9 B 6 C. 18 D. 8​