You are the head engine designer for a major automobile manufacturer. You know that the cars that roll off the assembly line have engines that operate between 325 C (600 K) and room temperature (300 Kelvin), and are only 49% efficient at converting the chemical energy of the fuel into the work of moving the vehicle. To improve the efficiency, you put your time, effort, and your stockholders' financial resources into trying to:

A. develop better lubrication for the moving parts of the engine;
B. design more efficient means of transmitting mechanical energy, e.g. reciprocating to rotary motion;
C. design an engine that doesn't "run so hot";
D. design an engine that runs "hotter"