When the temperature difference between the source and the sink increases, the efficiency of the heat engine will
(A) Increase
(B) Decrease
(C) Is not affected
(D) May increase or decrease depending upon the nature of the working substance.

Hint :Heat engine can be defined as the system which converts the heat or the thermal energy to the mechanical energy and ultimately the system is used to do the mechanical work by bringing the substance from the higher temperature to the lower state of temperature. Here we will see the effect of temperature on the heat engine.

Complete Step By Step Answer:
Temperature can be defined as the physical quantity which expresses the hot and the cold which is the manifestation of the thermal energy and present in all the matters. The temperature is the source of the occurrence of heat, a flow of energy when the body comes in contact with another which is colder or hotter.
The efficiency of the cycle can be given by $\eta = 1 - \dfrac{{{T_2}}}{{{T_1}}}$
Where, ${T_1} = $the temperature of the source
And ${T_2} = $the temperature of the sink
If the difference between the temperature of the source and the sink is increased that the temperature of the source increases or the temperature of the sink decreases the \[\dfrac{{{T_2}}}{{{T_1}}}\]value decreases and gives the increase in efficiency.
Hence, from the given multiple choices the option A is the correct answer.

Note :
Efficiency of the heat engine can also be given by the fraction of the heat absorbed and converted into work. Efficiency of no heat engine can have value equal to one, it is always less than one.