2. In Many-to-One Thread Model A. One user thread is mapped to many kernel threads B. One kernel thread is mapped to many user threads C. One kernel thread is mapped to many kernel threads D. One user thread is mapped to many user threads 3. Concurrent execution of producer & consumer processes requires A a shared buffer B. a synchronization requirement of buffer full check C. a synchronization requirement of "buffer empty" check D. choices (A) & (C) E. choices (A) & (B) & (C) 4. The short-term scheduler A. determines which jobs will be admitted to the system for processing B. selects from the jobs in memory, which are ready to execute, and allocates the CPU to one of them C. is executed frequently and hence needs to be fast D. choices (B) & (C)