Consider two threads T$1$ and T$2$ of a process P created using the pthread APIs in a Unix$/$Linux system. Which of the following statement$($s$)$ is$/$are true assuming a multi$-$core system?

Both T$1$ and T$2$ can invoke two different system calls at any point of time

Both T$1$ and T$2$ can invoke the same system call at any point of time

Both P and T$1$ can not invoke the same system call at any point of time

When the OS scheduler performs a context switch between T$1$ and T$2,$ the page table base pointer $($CR$3)$ register is not changed

When the OS scheduler performs a context switch between T$1$ and P$,$ the page table base pointer $($CR$3)$ register is not changed