The thermal efficiency of a nuclear power plant using a boiling water reactor is

Question

Assertion (A): The thermal efficiency of a nuclear power plant using a boiling water reactor is higher than of a plant using a pressurized water reactor. 

Reason (R): In a boiling water reactor, steam is directly allowed to be generated in the reactor itself, whereas in a pressurized water rector, steam is generated in a separate boiler by heat exchanger device using water of the primary circuit which absorbs the fission energy.

1. Both A and R are individually true and R is the correct explanation of A
2. Bothe A and R are individually true but R is not the correct explanation of A
3. A is true but R is false
4. A is false but R is true