Choose the logic gate represented by the following combination of log…

The correct answer is Option (3) → AND

Each input passes through a NOT gate, and the two inverted signals go into a NOR gate.

    \( y_1 = \overline{A} \)
    \( y_2 = \overline{B} \)

    \( \displaystyle y = \overline{\overline{A} + \overline{B}} \)

By De Morgan's theorem, \( \overline{\overline{A} + \overline{B}} = \overline{\overline{A}}\cdot\overline{\overline{B}} = A\cdot B \).

    \( \displaystyle y = A \cdot B \)

The output is 1 only when both inputs are 1, which is the AND gate. A check with the truth table:

    \( A = 0,\ B = 0:\ y_1 = 1,\ y_2 = 1,\ y = 0 \)
    \( A = 0,\ B = 1:\ y_1 = 1,\ y_2 = 0,\ y = 0 \)
    \( A = 1,\ B = 0:\ y_1 = 0,\ y_2 = 1,\ y = 0 \)
    \( A = 1,\ B = 1:\ y_1 = 0,\ y_2 = 0,\ y = 1 \)

Note: This question is from the pre-rationalised NCERT book (2022-23). The topic was removed from the latest NCERT book (2026-27), and it also appears to be out of the CUET 2026 syllabus.

NCERT (Pre-rationalised edition, 2022-23):
Logic Gates – “… (iii) AND Gate An AND gate has two or more inputs and one output. The output Y of AND gate is 1 only when input A and input B are both 1.”

Logic Gates – “… (v) NOR Gate It has two or more inputs and one output. A NOT- operation applied after OR gate gives a NOT-OR gate (or simply NOR gate). Its output Y is ‘1’ only when both inputs A and B are ‘0’, i.e., neither one input nor the other is ‘1’.”