The pairs below were meant to follow a single classification. Point out the one pair that slipped in wrongly.

Three of the pairs join a country to the city from which it is governed — Kathmandu for Nepal, Thimphu for Bhutan and Tokyo for Japan. The odd pair gives the great river that runs the length of Egypt; its capital is Cairo. The pair reads smoothly because the Nile is bound up with Egypt in the mind as tightly as any capital, but the group is held together by seats of government.