In the proof that the sum of rational numbers a/b and c/d, where a, b, c, and d are integers and b and d are non-zero, is a rational number, name the property that states that ad+bc and bd are integers. Enter 1 for option 1, 2 for option 2, and 3 for option 3.
Option 1: Associative Property
Option 2: Closure Property
Option 3: Commutative Property