The question in this exchange is the same as the one introduced in Structure 8. どちらも is used when there is no difference between N1 and N2.
A: 肉と 魚(と)では どちらが えいようが ありますか。
Which is more nutritious, meat or fish?
B: どちらも えいようが あります。
They are both nutritious.
A: ぎんざと しぶや(と)では どちらが にぎやかですか。
Which is more lively, Ginza or Shibuya?
B: どちらも にぎやかです。
They are both lively.
Lesson 16-7「両方とも 買いました。」
I bought both.