Which of the following sentences is the thesis statement?

select one:
a. i put a tremendous amount of time and effort into typing that paper, and i would appreciate it if you spent an equal amount of time and effort grading it.
b. if you understood how hard i worked on it, how much my friends liked it, and what a mistake you have made, then you would surely give me an "a."
c. after finishing my paper, i gave a copy to my friends to read. d. allow me the opportunity to argue for a better grade.