The Closure Property in mathematics states that when you perform an operation (in this case, multiplication) on two numbers from a certain set (here, integers), the result of that operation is also in that same set.
Since \( a \), \( b \), \( c \), and \( d \) are all integers, their products \( a \cdot c \) and \( b \cdot d \) must also be integers.
Therefore, the correct answer is:
2 (They are both integers.)