The shape of T-S diagram for Carnot Cycle is a

Answer: Option A

The Carnot cycle consists of
$$1.$$ Reversible isothermal expansion so, $$T=\mathrm{CONSTANT}$$
$$2.$$ Reversible adiabatic expansion so, $$S\left(\mathrm{entropy}\right)=\mathrm{CONSTANT}$$
$$3.$$ Reversible isothermal compression so, $$T=\mathrm{CONSTANT}$$
$$4.$$ Reversible adiabatic compression so, $$S\left(\mathrm{entropy}\right)=\mathrm{CONSTANT}$$