Switch a thread context is $\_\_\_\_\_\_.$

$9$

a$.$

harder in user$-$level threads compared with kernel$-$level threads

b$.$

easier in user$-$level threads compared with kernel$-$level threads

c$.$

none of these

d$.$

easier in kernel$-$level threads compared with hybrid threads

e$.$

easier in kernel$-$level threads compared with user$-$level threads