Write the vectorized solution for the gradient of the loss function, i.e., ∇(mae).
A) ∇(mae) = sign(y - y_hat) / n
B) ∇(mae) = (y_hat - y) / n
C) ∇(mae) = sum(sign(y - y_hat)) / n
D) ∇(mae) = sum(y_hat - y) / n