Select all the true statements. A multi-threaded program will always perform worse than a single threaded program on a single processor system due to the a overhead of creating and destroying threads. ob. It is cheaper to create and manage user-level threads than kernel-level threads. c. A program using kernel-level threads will always perform worse than a program using user-level threads. d. Two threads of the same process do not share the register values. Oe. Two threads of the same process do not share the global variables