Sentence 1: Mark had a report due on tigers for school. 
 Sentence 3: Mark really enjoyed looking at pictures of tigers 
 Sentence 4:  He also enjoyed all the books he got to read about tigers 
 Sentence 5:  Mark thinks he'll do very well on his report 
 Option 1: He spent all week doing research on tigers. 
 Option 2: He spent all week doing research on lions and did not realize the report was supposed to be on tigers.