A priority encoder has four inputs I₀, I₁, I₂ and I₃ where I₃ has the highest…

In a 4-to-2 priority encoder, the output is determined by the highest-priority input that is currently active (logic 1). While your prompt states that I1 = 1, the output cannot be determined without knowing the status of the higher-priority inputs (I2 and I3).

1. Dependency: If I1 = 1, the output will only be 01 if I2 and I3 are both 0.

2. Higher Priority: If I3 happens to be 1 at the same time, the output would be 11. If I2 is 1 (and I3 is 0), the output would be 10.

3. Ambiguity: Because the status of I2 and I3 is not defined in your question, there is no single fixed output. Furthermore, even if we assume I1 is the only active high-priority pin, the expected output 01 is not listed in options 1, 2, or 3.

Therefore, because the output is either conditional or simply missing from the provided list, "None of the above" is the correct choice.