If two engines are given the same amount of fuel, the more efficient engine can do more work than the less efficient engine can.
the following questions could be asked to make scientific or technological progress. which of the following questions is best
asked and answered as part of a scientific investigation, not as part of technological improvements?

a. how can efficient engines be built more cheaply?

b. how efficient can an engine be, in theory?

c. how can a more efficient engine be built?

d. how can the efficiency of an existing engine be improved?