Engines do work when chemical energy is changed from:

In a combustion engine, chemical energy is first converted to heat to cause the expansion of a fluid which then produces motion. In contrast, motor proteins are molecules that can convert the chemical energy released from adenosine triphosphate (ATP) hydrolysis directly into useful mechanical work.

Most likely a is the answer - because  you generate   38 atp's but also consume an atp.   each atp gives approx. less than 4 kcal so probably a is the closest answer.