Counting only assignment statements as operations, what is the order of complexity of the

following code fragment as a function of n$?$

x $=1$;

while $($x $<$ n$)$

x $=$ x $+$ x;

Question $16$Select one:

a$.$

O$(1)$

b$.$

O$($n$)$

c$.$

O$($log n$)$

d$.$

O$($n$2)$