Solve the Problem $$e = \frac { Q _ { h } - Q _ { C } } { Q _ { h } } \text {, }$$

Solve the problem.
-A heat engine is a device that converts thermal energy into other forms. The thermal efficiency, e, of a heat engin defined by
$$e = \frac { Q _ { h } - Q _ { C } } { Q _ { h } } \text {, }$$
where $\mathrm { Q } _ { \mathrm { h } }$ is the heat absorbed in one cycle and $\mathrm { Q } _ { \mathrm { C } }$ , the heat released into a reservoir in one cycle, is a constant. Find $\frac { d e } { d _ { h } }$ .

A) $\frac { \mathrm { de } } { \mathrm { dQ } _ { \mathrm { h } } } = - \frac { \mathrm { Q } _ { \mathrm { C } } } { \mathrm { Q } _ { \mathrm { h } } { } ^ { 2 } }$
B) $\frac { d e } { d Q _ { h } } = \frac { 1 } { Q _ { h } ^ { 2 } }$
C) $\frac { d e } { d Q _ { h } } = Q _ { h } - Q _ { C }$
D) $\frac { \mathrm { de } } { \mathrm { dQ } _ { \mathrm { h } } } = \frac { \mathrm { Q } _ { \mathrm { C } } } { \mathrm { Q } _ { \mathrm { h } ^ { 2 } } }$