Logic Gates Questions

A circuit has two inputs A and B and output C. The truth table shows C is 0 only when both A and B are 0, and C is 1 otherwise. This circuit represents:

The logic circuit shown below has the input waveforms '$A$ ' and '$B$ ' as shown. Pick out the correct output waveform.

A logic gate circuit has two inputs $A$ and $B$. Both are passed through NOT gates, then through a NAND gate, and finally through another NOT gate. This combination yields:

Truth table for system of four NAND gates as shown in figure (where $A,B$ are inputs to a NAND, its output splits to two NANDs, and their outputs go to a final NAND) is equivalent to: