-OLD MAN AND THE SEA- How much of what we call courage is really motivated by the hope of a reward? In other words, if Santiago had known that he had some chance of success, would his fight have been tainted by selfish motives?

yes his fight would be tainted with selfish motives if he known he had a chance if success

the following key ideas correctly express the key sentence.

restate key idea: most people can learn to swim in ten short lessons.

restate key idea: the majority of water-accident victims require mouth-to-mouth breathing.

restate key idea: an empty, tightly closed gallon jug will support a tired swimmer.  

restate key idea: first aid is to prevent accidents as well as assist in rescue.

explanation: the key idea needs to have the same topic as the key sentence (drowning and safety).

noun phrase/ noun phrase/ verb phrase/ noun clause/ awnsers are in order to questions above