The output of a $NOR$ gate is $HIGH$ when

The circuit diagram shown here corresponds to which logic gate?

Logic gates are constructed by

For the following combination of logic gates,when all the three inputs $A$,$B$ and $C$ are first 'high' and then 'low',the output $Y$ will be respectively.

$A$ 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?

The logic circuit below has the truth table, same as that of