The least relevant to the overall meaning of the passage is requiring service hours would also be a good move for the high school's reputation among the community.
The purpose of the passage, is to inculcate the habit of service done by students of the high school. It is to make them aware of their duties, as responsible citizens of the country and give something back to the community.
It is to cultivate compassion and kindness among the children and help them understand their social obligation towards the community.
The above detail is irrelevant, because it doesn't matter if service hours helps in improving the reputation of the school.
Inculcating service hours for students should be irrespective of the school's image, and should be done out of duty towards the community.