Location A - London Overground between Hoxton and Haggerston - Bridge over Durston Road / Regents Canal
Location B - London Overground between Hackney Central and Homerton view from Morning Lane - Route to St John at Hackney Church, on Q2 Cycle Route
Location C - Piccadilly Line between Hounslow East and Hounslow Central - Alexandra Road Bridge
Location D - Metropolitan Line between Chorleywood and Chalfont & Latimer - Accommodation and access Overbridge as viewed from S Stock train
Link they are all locations between two stations starting with the same first letter.
As 3 are beginning with the letter H and 1 with the Letter C
The odd one out would be D as is between two stations beginning with the letter C.
The Northernmost one in the set, (as would be between two stations beginning with the Letter H) - London Overground between Headstone Lane and Hatch End.
Other paired stations beginning with the letter H as could be included in this set would be:
Hounslow Central - Hounslow West
Hounslow West - Hatton Cross
Hatton Cross - Heathrow Terminal 4 (Furthest South)
Hatton Cross - Heathrow Terminals 2&3
Heathrow Terminals 2&3 - Heathrow Terminal 4
Heathrow Terminals 2&3 - Heathrow Terminal 5 (Furthest West)
Hayes & Harlington - Heathrow Terminals 2&3
Harrow & Wealdstone - Headstone Lane
Homerton - Hackney Wick (Furthest East)