Darius created a factor tree and wrote the prime factorization of 60 shown here. A factor tree of 60. 60 branches to 4 and 15. 4 branches to 2 and 2. 15 branches to 3 and 5. 60 = 2 × 3 × 5 What is Darius's error? Darius should have started the factor tree with 2 × 30. Darius did not complete the factorization; 5 is a composite number. Darius should have expressed 15 as 5 × 5, not 3 × 5. Darius should have expressed 60 as 22 × 3 × 5, not 2 × 3 × 5.