The London zoo is a zoological garden the same as in Greek as well as just a zoo so both answers would be correct.
"I brought my moth up to the ezoo, to see the lion and the kangaroo, there are females and hemales of every hue, up in the zoological gardens" Brendan Beehan. Favourite Dublin ditty.
... and importantly, the usage there is "zoological gardens" (gardens in the plural), so "Where are the zoological gardens?" should also be accepted.
yes I remember that ditty from school, still brings a smile when I hear it. I answered the question in English " where is the zoological garden" but it would only accept " where is the zoo" perhaps they don't realise that the sentence is word for word the same in English.