It should be A sorry if I’m wrong
Answer:

Explanation:
We have series and parallel combination of two resisters
and
.
Series combination is
and Parallel is
Now dividing series equivalent resistance by parallel resistance gives us
.
Note! series Combination is simply superposition of two elements (resisters in this case ) in a circuit.
Answer:
Fuel cells have a higher efficiency than diesel or gas engines.
Most fuel cells operate silently, compared to internal combustion engines.
Fuel cells can eliminate pollution caused by burning fossil fuels.