3. (10 pts) Write a multithread C program to count the number of prime numbers within a given range [low,high] (inclusive), where the program should be able to take in the number of threads as an argument. You may use this single thread program in anyway you like. ( Here is a reference implmentation ( executable only), and you can check your results against this one to see if they match.) 4. (10 pts) Write a simple test program to find out the parent process id of a process before and after its parent process terminates. Based on your test results, answer the following question: what is a process's parent process after its original parent process terminates?