Substituting \(1\) for \(x\) in the equation \(5x + 3 = x \cdot 5 + 3\) is a test case that demonstrates the Commutative Property of Multiplication.
This is because \(x \cdot 5\) can be rewritten as \(5 \cdot x\), illustrating that the order of multiplication does not affect the outcome. So, the correct response is:
The Commutative Property of Multiplication.