Answer: Dear Headmaster,
I have been wanting to let you know of some things that some students have been doing for the past week. There is a student in the 5th or 6th grade that has been flooding the bathrooms and taking away the soap dispensers in both the girl and boys bathrooms. There is also a couple of students from the basketball team who have been bulling other students and are planning on graffiti the school on Sunday. Please take care of these kids so that way kids still want to come to this school.
Sincerely,
your students
The answer is the last one :)
True a gerund can be the object of a preposition
