Manuel created a factor tree and wrote the prime factorization of 60 shown below. A factor tree of 60. 60 branches to 4 and 15. 15 branches to 3 and 5. The equation is 60 = 3 times 4 times 5. What is Manuel's error? He did not include 15 in the prime factorization. He did not find the prime factors of 4. He should have started the factor tree with 2 times 30. He should not have found the factors of 15.