Question $1$: Which command will give the standard deviation for each column in a $5-$

row by $-10$ column matrix Z$?$

A$.$ std$($Z$($:$))$

B$.$ std$($std$($Z$))$

C$.$ std$($Z$(1$:$5,$ :$))$

D$.$ std$($Z$)$

$(1)$

Question $2$: Which command will return the positive numbers in a $10-$by$-10$ matrix A$?$

A$.$ A$($A $>0)$

B$.$ sum$($A $>0)$

C$.$ nnz$($A $>0)$

D$.$ A$($A$<=0)$

E$.$ A $>0$

$(1)$