Sentence:  How could the rich , for whom life was made so simple , ever understand the subterfuges , the lies , the frauds , the errors , sins and even crimes to which the poor were driven in their <WSD>efforts</WSD> to overcome the great advantages the rich had in the race of life ? 
Meaning of the word marked with <WSD> tags:  earnest and conscientious activity intended to do or accomplish something