QUESTION $20$

To turn on and off this OUTPUT will require the folkwing Push Button sequence.

A and $B$ on $\frac{?}{C}$ and $D$ off

All ot the above

A or $B$ on $\frac{?}{C}$ and $D$ off

A or B on$/$C or D ofl

None of the above

A and $B$ on $\frac{?}{C}$ or $D$ oft