Please help


One of the steps Dave used to solve an equation is shown below.

3x+9=21

3x+9-9=21-9


Which statement describes the procedure Dave used in this step and identities the property that justifies the procedure?

ADave rearranged the terms. This procedure is justified by the commutative property.

BDave subtracted 9 from both sides. This procedure is justified by the additive property of equality.

CDave rearranged the terms. This procedure is justified by the associative property.

DDave subtracted 9 from both sides. This procedure is justified by the additive inverse.