In the various implementations of threads

A$.$ Java VM $1\mathrm{.}1$ is a single process with user level threads.

B$.$ UNIXs $($like Mac OS X$)$ make no distinction between a process and a thread.

C$.$ Linux has a many$-$to$-$one thread to process relationship.

D$.$ The Cloud Kernel has a one$-$to$-$many thread$-$to$-$process relationship.