$24$ What describes a monitor in a process synchronization?

Choose $2$ answers.

A compiler uses $P$ and $V$ operations on semaphores to enforce the features of a monitor.

Signal operation on a monitor condition variable causes the executing process to be placed on a waiting queue.

A monitor is a high$-$level synchronization primitive implemented using $P$ and $V$ operations.

Multiple processes at a time can execute code inside a monitor to access the internal variable.