- I have spoken with the school nurse about this issue, and she says that eating too quickly is a very unhealthy habit.
- Those of us who take part in after-school activities or have jobs often don’t get home until late in the evening.
The question asks for supporting arguments, both the sentences "It is my belief that the lunch period at Mountain Vista High School is not long enough and should be lengthened." and "In addition, the lunch period should be extended because it would give students additional time to study or finish homework." are not supporting arguments, they <em>are </em>the argument. The sentence "I truly hope that you take my arguments under consideration, Principal Corte." is more of a closing statement.
The two remaining sentences, in bold above, are supporting arguments because they have asked others for more information. Whether that be an "expert" like the nurse, or people who are going through the same thing "witnesses" like the students.
So, out of all the selections in blue, the two I have in bold above are the correct options.