On the London underground, which is the only line 2 connect at some point with every other line on the system?

Question

On the London underground, which is the only line 2 connect at some point with every other line on the system?

Answer 1

It could be the central line

Answer 2

It's the Jubilee. It's the only one that connects with both the Waterloo and City and the East London (the Waterloo and City only has two stations and the East London is rather isolated).

Answer 3

It has to be the Circle Line. The yellow one.

Answer 4

just hop on any train they all go somewhere

Answer 5

The pencil line I have just drawn on the map of the London Underground printed on the inside back cover of my diary!

Answer 6

The circle line