Which expression illustrates the associative property of addition?

The associative property changes the grouping of numbers being added without changing their order or value: (a + b) + c = a + (b + c). In choice C, subtracting 12 is the same as adding −12, so (3 + 19) − 12 can be regrouped as 3 + (19 − 12). The other choices change signs or rearrange the numbers.

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