(Exercise 4.3) Which of the following components of program state are shared across threads in a multithreaded process? a. Register values b. Heap memory c. Global variables d. Stack memory (Exercise 4.4) Can a multithreaded solution using multiple user-level threads achieve better performance on a multiprocessor system than on a single processor system? Explain. (Exercise 4.6) Is it possible to have concurrency but not parallelism? Explain. (Exercise 4.9) A system with two dual-core processors has four processors available for scheduling. A CPU-intensive application is running on this system. All input is performed at program start-up, when a single file must be opened. Similarly, all output is performed just before the program terminates, when the program results must be written to a single file. Between startup and termination, the program is entirely CPU-bound. Your task is to improve the performance of this application by multithreading it. The application runs on a system that uses the one-to-one threading model (each user thread maps to a kernel thread). a. How many threads will you create to perform the input and output? Explain. b. How many threads will you create for the CPU-intensive portion of the application? Explain. (Exercise 4.10) Consider the following code segment: After running this program, answer the following questions. a. How many processes do we have? b. How many threads do we have (including main threads)