Aimee must add together the following numbers: 3.50 + 4.00 + (−1.25) + (−7.50) + 5.25 + 2.00

As her first step, Aimee writes:

(3.50 + (–7.50)) + (–1.25 + 5.25) + (4.00 + 2.00)
Which is the best explanation of what Aimee did in this step?
A. Aimee used the Associative and Commutative Properties to put opposite numbers together.
B. Aimee used the Identity Property to put numbers with the same values after the decimal point together.
C. Aimee used the Associative and Commutative Properties to put numbers that are easy to add next to each other.
D. Aimee used the Inverse Property to pair each positive decimal with a negative decimal so that they will cancel out.