QUESTION 23 Which one of the following directly controls operations on computer hardware? O A. operating system kernel O B. application programs O C. the command interpreter QUESTION 24 Which of the following statements is true? O A. Named pipes do not allow bi-directional communication OB. Only the parent and child processes can use named pipes for communication OC. Named pipes allow bi-directional communication OD. Ordinary pipes are more powerful than ordinary pipes QUESTION 29 Which one of the following modes for mapping user threads to kernel threads must be used if the operating system does NOT support multiple kernel threads? O A. many-to-many O B. two-level OC. one-to-one O D.many-to-one QUESTION 31 Multiple threads within a process O A. must execute within disjoint parts of the shared program O B.will always execute the same sequence of instructions OC. may execute different sequences of instructions within any part of the shared program