I've come back to this one again, and I'm sure the question is incomplete.
Quid, I'm going to respectfully disagree with you on this one - you get the OAT from the thermometer in the aircraft, which means it will be the temperature at the aircraft's altitude. So I think the intention is that the temperature at height 1760' is -25 degrees. But there is certainly ambiguity in the question, and your interpretation definitely could be considered correct.
But one thing which is missing is the airfield elevation. Without knowing this, we can't even guess what the ISA temperature is (we've both assumed sea level). If the airfield elevation is reasonably high, then the ISA temperature will be much lower than we've been assuming. The ISA deviation will therefore be smaller, and the indicated altitude will not differ from the actual altitude by so much. I think this is why we can't get to any of 1515's answers.
1515, where did the question come from? Is there any chance you could go back and check that you haven't missed some details?
FFF
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