Substituting 1 for x in the equation \(5x + 3 = x \cdot 5 + 3\) tests the Commutative Property of Multiplication. This property states that changing the order of the factors does not change the product. In this case, both sides of the equation involve the multiplication of \(x\) and \(5\). Therefore, the correct response is:
The Commutative Property of Multiplication