Answer:
d.less non-renewable gas will be used to produce heat
Step-by-step explanation:
Gas heaters most often use naturally occurring, non-renewable gas as a source of power.
Efficient gas heaters use less gas to generate maximum heat as compared to non or less efficient gas heaters.
Hence, efficient gas heaters will ensure that less non-renewable gas that serves as a source of power is used to produce heat, thereby prolonging the life span of the natural reserve of the gas.
The correct option is d.