please explain step by step.

'What is the running time of the given routine?

function IsPrime$($N: integer$)->$ boolean

if $N1$ then

return FALSE

endif

if $N=2$ then

return TRUE

endif

if Nmod$2=0$ then

return FALSE

endif

i :$=3$

while i t i $$ N loop

if $N$ mod $i=0$ then

return FALSE

else

$i$:$=i+\frac{2}{\frac{?}{?}}$ skip even numbers since we

already checked for $2$

endif

end loop

return TRUE

end function

a$.$ Constant

b$.O(logN)$

c$.O(N)$

d$.O(\sqrt[\phantom{2}]{n})$