Which of the following logic gates is a universal gate?

$A$ logic gate circuit has two inputs $A$ and $B$ and output $Y$. The voltage waveforms of $A, B$ and $Y$ are shown below. Identify the logic gate circuit.

The output $W$ for the given logic circuit is:

Assertion: The logic gate $NOT$ can be built using a diode.
Reason: The output voltage and the input voltage of the diode have a $180^o$ phase difference.

The diagram of a logic circuit is given below. The output of the circuit is represented by:

Logic gates are constructed by