Despite having the greatest possible theoretical efficiency, why does the source say the ideal Carnot engine is unrealistic for any practical application?

1. Reaching Carnot's maximum efficiency requires that every step of the cycle proceed reversibly, which in turn requires the process to happen infinitely slowly. 2. An infinitely slow cycle delivers essentially no power, since power is work delivered per unit time. 3. The source makes this point using the drinking-bird toy as an example: like that toy, the ideal Carnot engine has zero power, making it unrealistic for any application. 4. No temperature in this discussion goes below absolute zero, and the engine does not violate energy conservation by producing more work than it receives, ruling out options B and C. 5. The zero-power limitation is about the rate of operation, not about the engine being limited to one cycle, ruling out option D. _Source: OpenStax College Physics (CC BY 4.0), Ch 15 "Thermodynamics", section 15.4 Carnot's Perfect Heat Engine: The Second Law of Thermodynamics Restated_