1. In the standard diode-resistor logic circuit used for this question, the output is taken across a resistor, while the inputs are connected through diodes in such a way that:

   • if any one input is high, the corresponding diode conducts,
   • this makes the output high.

2. Let the two inputs be $A$ and $B$.

3. Truth table analysis for this diode logic:

   • If $A=0, B=0$: no diode drives the output high, so output $Y=0$.
   • If $A=1, B=0$: diode from $A$ conducts, so $Y=1$.
   • If $A=0, B=1$: diode from $B$ conducts, so $Y=1$.
   • If $A=1, B=1$: both inputs are high, so $Y=1$.

4. Therefore the truth table is:

5. This matches the logical operation:

which is the OR operation.

6. Option-wise check:
   • A: AND $\rightarrow$ incorrect
   • B: NOR $\rightarrow$ incorrect
   • C: OR $\rightarrow$ correct
   • D: NAND $\rightarrow$ incorrect

Hence, the circuit performs the OR logic operation.