Correct option is (a) Power signal with P∞ = 1
To elaborate: If a signal has E∞ as ∞ and P∞ as a finite value, then the signal is a power signal. If a signal has E∞ as a finite value and P∞ as ∞, then the signal is an energy signal.
|x (t)| = 1, E∞ = \(\int_{-∞}^∞ |x(t)|^2 \,dt = ∞\)
So, this is a power signal not an energy signal.
\(P_∞ = lim_{T→∞} \frac{1}{2T} \int_{-T}^T |x(t)|^2 \,dt = 1.\).