$2)$ The transition $($ready $->$ running$)$ of a process p is caused by $\_\_\_\_\_.(4$ points$)$

a$.$ the OS

b$.$ the process p itself

c$.$ some other process

$3)$ The transition $($running $->$ blocked$)$ of a process p is caused by $\_\_\_\_\_.(4$ points$)$

a$.$ the OS

b$.$ the process p itself

c$.$ some other process

$4)$ The transition $($running $->$ ready$)$ of a process p is caused by $\_\_\_\_\_.(4$ points$)$

a$.$ the OS

b$.$ the process p itself

c$.$ some other process

$5)$ The transition $($blocked $->$ ready$)$ of a process p is caused by $\_\_\_\_\_.(4$ points$)$

a$.$ the OS

b$.$ the process p itself

c$.$ some other process