"The professor's office is in Paris."
Translation:مَكْتَب اَلْأُسْتاذ في باريس.
both answers 2&3 are correct - The professor's office is in Paris. 2. مَكْتَب اَلْأُسْتاذ في باريس 3. مَكْتَب اَلْأُسْتاذة في باريس
That's problematic because for for the Duolingo only one of them is considered correct, which is not true
I've passed thru such similar incidents where more than one answer is possible and all are accepted (think of "you" in English, it's used for singular and plural). I guess they know it already but they don't want to confine the user to a specific line of thought unless it is necessary for some grammatical need maybe