Which one is the correct way of standardizing i.i.d x_i's to a i.i.d standard normal in R

1) z<-(x-mean(x))/sd(x)

2) z<-(x-mean(x))/ (sd(x)/sqrt(n)) = (x-mean(x))*sqrt(n)/ sd(x)

3)z<-(x-mean(x))/ (sd(x)/sqrt(n/n-1)) = (x-mean(x))*sqrt(n/(n-1))/ sd(x)