Assume no change in the labour force. In the 2030s, physical capital increased by 20% and GDP increased by 15%. In the 20403, physical capital increased by 20% and GDP increased by 10%. This is consistent with marginal product of capital. If asked about total factor productivity, we 0 negative; can infer it decreased. 0 negative; cannot infer whether it increased or decreased. 0 diminishing; can infer it decreased. 0 diminishing; cannot infer whether it increased or decreased