144
Step-by-step explanation:
To be a perfect square trinomial, c must be a perfect square. 144 is the only option out of the given four that is a perfect square. A negative cannot be a square because a negative times a negative is a positive, so A and B are null. 48 is not a perfect square (two of the same whole numbers will not multiply exactly to 48). Therefore, the only option left is 144.