What does the following code snippet do:

$...$

rc $=$ fork$()$;

if $($rc $==0)\{$

$...$

$\}$ else $\{$

$...$

$\}$

It creates a clone of the currently executing process, which begins to execute in parallel with the current process. Unless there is an error creating the new copy of the process, only code in the if branch will be executed by both processes.

It creates a clone of the currently executing process. The child process waits until the original process completes. Code in the if branch will finish executing first.

It creates a clone of the currently executing process, which begins to execute in parallel with the current process. The original process continues un$-$interrupted. Code in both the if and else branches will be executed in parallel.

It creates a clone of the currently executing process. The original process pauses execution until the child process completes. Code in the else branch will finish executing first.