Answer: The correct option is (C) Associative Property of Addition.
Step-by-step explanation: We are given to name the property that the following equation illustrates:

Let us consider that
a = -5, b = 8 and c = 10.
Then, equation (i) becomes

which is the associative property of addition for the real numbers a, b and c.
Thus, the given equation illustrates the associative property of addition.
Option (C) is CORRECT.