Sari applied the distributive property using the greatest common factor to determine the expression that is equivalent to 84 +40. Her work is shown below. Factors of 84: 1, 2, 3, 4, 6, 7, 12, 14, 21, 28, 42, 84
Factors of 40: 1, 2, 4, 5, 8, 10, 20, 40

84 + 40 = 2 (42 + 20)

What statement best describes Sari’s error?
A. Sari did not use correct factors for 84 in the equation.
B. Sari did not use correct factors for 40 in the equation.
C. Sari did not use two equivalent expressions in the equation.
D. Sari did not use the greatest common factor in the equation.