The Associative Property of Addition states that the way in which numbers are grouped when added does not change the sum. In symbolic form, it can be expressed as:
\[ (x + y) + z = x + (y + z) \]
From the options you provided, the expression that correctly demonstrates the Associative Property of Addition is:
\[ (x + y) + z = x + (y + z) \]
If you are looking for a specific choice from the list you provided, the closest one to the Associative Property of Addition is:
\[ (x+y)+z+r = x+(y+z)+r \]
This expression shows that when three numbers (x, y, and z) are added together, grouping them in different ways (either (x + y) + z or x + (y + z)) does not change the sum, which is characteristic of the Associative Property.