Semiconductor Electronics question for NEET (NEET 2021), with solution

Answer: (C) see figure

The circuit gives
$$y = (A \cdot B) + \overline{(B \cdot C)}$$
(an AND gate on A, B and a NAND gate on B, C, both feeding an OR gate).

From the waveforms, B is high only between $t_2$ and $t_4$, and during exactly that interval C is low. So $B$ and $C$ are never high together: $B \cdot C = 0$ at all times, and the NAND output $\overline{B \cdot C} = 1$ throughout.

An OR gate with one input permanently at 1 gives $y = 1$ at all times: a constant $5$ V, which is option (3).

Solution by Sreeraj P, M.Sc Physics