Activity R on a CPM network has predecessors M and N $,$ and has successor S $.$ R has duration $5.$ N$\text{'}$s late finish is $18,$ while M$\text{'}$s is $20.$ S$\text{'}$s late start is $14.$ Which of the following is definitely true?

$N$ is a critical activity.

$S$ is a critical activity.

$R$ is critical and has zero slack.

$R$ has no slack but is not critical.

The set of times cannot all be possible.

Who is responsible for the success and failure of a project?

the CEO

the program manager

the project manager

the project sponsor

the functional manager