Which one of the following is the Boolean expression for $NOR$ gate?

In the Boolean algebra,$(\overline {\bar A \cdot \bar B} ) \cdot A$ is equal to:

Which of the following represents a $NAND$ gate?

The combination of logic gates shown below becomes:

The truth table for the circuit given in the figure is

$A$ building has two overhead water tanks, each fitted with a sensor $(S_1, S_2)$ which goes to $0$ when the water level in the tank falls below a set value and remains $1$ otherwise. $A$ common pump is used to raise water from an underground storage tank to these overhead tanks. Of the following circuits, which one will turn on $(P = 1)$ the pump only when at least one of the tanks has a water level below the set value?