For a heat engine operating between the same two reservoirs

(a) \(\eta_{\text {irrev }}<\eta_{\text {rev }}\)

(b) \(\eta_{\text {irrev }}>\eta_{\text {rev }}\)

(c) \(\eta_{\text {irrev }}=\eta_{\text {rev }}\)

(d) \(\eta_{\text {irrev }} \geq \eta_{\text {rev }}\).