Sentence 1: Tom saw a friendly dog while walking through the city. 
 Sentence 3: He visited an animal shelter 
 Sentence 4:  He looked at every dog 
 Sentence 5:  He took home a great dog and made a new best friend 
 Option 1: He wanted a dog but knew he couldn't take care of one. 
 Option 2: He decided he wanted a dog of his own.