1. The problem shows a parallelogram ABCD with sides AB and CD opposite each other, and sides AD and BC opposite each other. 2. In a parallelogram, opposite sides are equal in length. 3. Given that BC = 5 cm, and BC is opposite to AD, it follows that AD = 5 cm. 4. Therefore, the correct answer is A: AD = 5 cm. This uses the property of parallelograms that opposite sides are equal in length.