In the following combination of logic gates, the output $Y$ can be written in the terms of inputs $A$ and B as

In common emitter mode of a transistor, the current gain is 8 . The input impedance is $25 \mathrm{k} \Omega$ and load resistance is $75 \mathrm{k} \Omega$. The power gain is

If the internal resistance of cell is negligible then current flowing through the circuit is

Which of the following logic gates is called as Universal gate?