# What is the number of transition amplitudes needed to describe an $n$-qubit state?

In describing quantum computers page in the fourth quick quiz it asks "An n-qubit state vector can contain up to $$2^n$$ amplitudes. What’s the largest number of transition amplitudes we’d need to represent any quantum operation on n qubits?"

My question is why is $$4^n$$ is wrong and $$(2^n)^2$$ is right, when $$4^n = (2^n)^2$$? Or is my math just wrong? I tried $$n=1,...,5$$. Isn't $$(2^n)^2 = 2^{n\cdot 2} = 2^{2n} = (2^2)^n = 4^n$$?