In paragraph 5, the idiom stick it out means a. to keep going. b. to remain bored. c. to stop playing. d. to start practicing.

The idiom stick it out means;

A. to keep going.  

Replace each phrase with the anser choices. A. is the only one that makes sense in the context of the whole paragraph

Teresa agreed to keep going for the rest of the season

the guest is my guess

the answer should be d) he was one of those young thousands who greeted the war with a certain amount of relief, welcoming the liberation from webs of tangled emotion" since it is the best option because it shows his desire to free himself. 

hope this answer you! have a great day.