Which one of the following is non-selective herbicide

Answer: Option C

Paraquat is one of the non-selective herbicides while others Alachlor, Butachlor and Atrazine are selective Herbicides.
Non-selective herbicides are those that can affect and kill any plant they will come in contact with not like selective ones that will target only a specific type. Non-selective can harm the main crop plant also on the application.