Canary Wharf is the key business district of Docklands, but the larger Isle of Dogs it is at the northern end of is all part of Docklands, which also covers the Royal Docks, and other former docks like Canada Water.
So all three London options of that question are in Docklands, and none are fully exhaustive. The answer is "guess which half-right answer the quiz maker chose".
For question 10, as there is more than one cathedral in London, it would be more correct to say "Which of the following is A cathedral in London" (rather than THE cathedral). There is Westminster cathedral also, for example.
So all three London options of that question are in Docklands, and none are fully exhaustive. The answer is "guess which half-right answer the quiz maker chose".