a)  In languages that support multi-threading, a thread's execution typically
    occurs inside some kind of ``callable'' construct such as a function or method.

b)  The relationship between fork() and wait() is much like
    the relationship between pthread_create() and pthread_join().

c)  Even though Linux's implementation of POSIX Threads allows for the
    creation of multiple threads, only one of the these threads can be in the
    `RUNNING` state at a time, even when the underlying machine uses 
    a multiprocessor system.

d)  Context switches between 2 threads that are part of the same process
    are usually cheaper than context switches between 2 threads that belong to 
    different processes.

e)  Abstractions such as mutexes and semaphores may fail in situations where 
    a system is under high load and thus needs to preempt threads more often, which 
    increases the likelihood that they are preempted even while they are executing 
    in a critical section.