The combination of `'NAND'` gates shown here under (figure) are equivalent to

Options

A. An `OR` gate and an `AND` gate respectively
B. An `AND` gate and a `NOT` gate respectively
C. An `AND` gate and an `OR` gate respectively
D. An `OR` gate and a `NOT` gate respectively

Answer

A

Explanation

`C=bar(bar(A).bar(B))=bar(bar(A)+bar(B))` (De Morgan's theoram)
Hence output `C` is equivalent to `OR` gate.

`C=bar(bar(AB).bar(AB))=bar(bar(AB)+bar(AB))=AB+AB=AB`
In these case output `C` is equivalent to `AND` gate.