D. Neither of these. Thermal energy and temperature only increases through nonconservative forces, not mechanical energy.
This looks like a text book question without the specifics. What system? What kind of system? It looks like a question taken from a chapter that is looking for the specific wording from that chapter. Without knowing the book, subject, chapter or system, my best guess is C.
There CAN be… Mechanical work implies machinery, friction causes heat. If the machine is designed to create thermal energy, IE heat, working on it might improve it. If it is designed to mechanically do anything, improper mechanical work can create friction and heat. A and B are the same thing, an increase in temperature is an increase in thermal energy. Any mechanical work on any machine CAN cause heat, wheather it is supposed to or not.