In the following circuit, the output $Y$ becomes zero for the input combinations.

• A

  $A=1, B=0, C=0$
• B

  $A=0, B=1, C=1$
• C

  $A=0, B=0, C=0$
• Correct answer
  D

  $A=1, B=1, C=0$

Solution

The output of the circuit is $Y=\bar{A}+\bar{B}+C$
$Y=\overline{\mathrm{A} \cdot \mathrm{B}}+\overline{\overline{\mathrm{C}}}=\overline{\mathrm{A}}+\overline{\mathrm{B}}+\mathrm{C}$ If the output is zero, i.e. $Y=0$ then $A=1$ $B=1$ and $C=0$

Hence, the correct answer is option: 'D'.