Answer:
A certain cool-headedness had come to him;
[D]oggedly he swam in that direction, swimming with slow, deliberate strokes, conserving his strength.
Explanation:
These details 'a certain..him', '[D]oggedly...strength' from the narration display that Rainsford sensible and rational person who has the ability to do well in dangerous moments. <u>The qualities of being 'cool-headed', 'swimming with the slow', and the ability to 'conserve his strength through deliberate strokes' clearly reflect that he is a calm and composed individual who can conquer the dangers and difficulties</u> coming his way through his astute and rationality. The phrases 'he wrestled with all his power', 'he struck out with strong strokes', 'struggled up to the surface and tried to cry out' substantiate the above claim.
It's 3. All the other answers are opinons and not provable by fact.
