What do most composites and plastics have in common? they are electrically non-conductive. they are crystalline. they are based on a carbon molecular structure. they are malleable.

The big glowy thing is called the sun it is a star in our galaxy and is over 1 million degrees

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.

Iwould say the answer is d