Carbon monoxide poisoning can be prevented by

a. always making sure your car's exhaust system is working properly and never leaving a car running in a garage
b. never leaving an open bottle of hair spray in the car
c. checking your vehicle's engine at least once a month
d. always keeping your ventilating system on low

i would say that these are the two thesis statements best for a literary analysis essay on recurring themes in shakespeare's romeo and juliet:

1.  in romeo and juliet, shakespeare demonstrates that love comes in a variety of forms, be it romantic, familial, or between friends.

2.  shakespeare explores the struggle for identity through the character of juliet in his play romeo and juliet.

the other theses aren't reoccurring in this play. 

explanation:

the purpose of the heading in the passage is to identify who is telling the story.

this excerpt is part of the book sugar changed the world (2010) written by marc aronson and marina budhos. as the book has been written by two people, the heading "marc" indicates that this specific excerpt is being narrated by aronson. in the fragment, marc describes his grandfather's story after hearing it from his cousin. however, there are other excerpts where budhos is the one that tells the story of her family.

aronson and budhos, who are husband and wife in real life, decided to write sugar changed the world when they found out how sugar, which had an important role in slavery and economy, changed their ancestors' lives.