Sentence 1: Buck bragged he was the best swimmer on the team. 
 Sentence 3: The class responded with jeers and derision at Buck's arrogance 
 Sentence 4:  They hoisted Buck from the diving board by his trunks 
 Sentence 5:  Even the slowest team member could swim faster than him now 
 Option 1: He bet the whole class would eventually improve over time. 
 Option 2: He bet the whole class he could swim faster than them all.