18. (20 points). For each statement below, circle either "true" or "false" as appropriate. Correct answers are worth one point, incorrect answers lose one point. (a) true false The set of all Turing machines is a countably infinite set. (b) true / fabe A malti-track Turing mhineis oe ponerk Turing ma- chine. (c) true false All languages are recursively enumerable. (d) true false The set of all linear-bounded automata is a countably infinite set. (e) true false If the language L is not recursively enumerable, then L is regular. (f) true false If the language L is not recursively enumerable, then L is recursive. (g) true false The set of all JPEG images is a countably infinite set (h) true false The word "automaton" is plural. (i) true false The set of all instantaneous descriptions of a Touring machine is a countably infinite set (j) true false The set of all finite-state machines is a countably infinite set R+W+B-10: 2R+OW+1B