Help. Can somebody please answer the question in the photo?

Is there a picture to go along with this

If the heat engine is a perfect carnot cycle engine, thenefficiency = (t2-t1)/t2   where t1=temperature of cold reservoir ( ° k) = 135            t2=temperature of hot reservoir ( ° k)   = 325thereforeefficiency = (t2-t1)/t2 = (325-135)/325 = 0.5846 = 58%  note: this is the theoretical maximum efficiency of a perfect heat engine.   real-life engines do not achieve this value.

We have no idea what the graph shows, or why it may be accurate,  because we can't see the graph.on a different subject, choice ' d ' is the only true statement among the choices.

B. elliptical. as in oval. 0 (==