Which of the following is false? Justify your selected answer.

a$.100$ n log n is O$($n log n$/100)$

b$.($log n$)$ is O$($log log n$)$

c$.$ If $0<$ x $<$ y then nx is O$($n$^$y$)$

d$.2$n $!=$ O$($n$*$k$)$