Consider the following Carnot engines : $$ Engine A: Th $=1500$ K$,$ Tc $=500$ K $$ Engine B: Th $=1000$ K$,$ Tc $=200$ K $$ Engine C: Th $=3000$ K$,$ Tc $=1000$ K$.$ Which two engines have the same thermal efficiency? $$ A$)$ A and B $$ B$)$ B and C $$ C$)$ A and C $$ D$)$ None