Fewest Colours
Understand the puzzle
The exact puzzle
A map has five regions: A, B, C, D, E. Regions that share a border may not be the same colour. The borders are: A touches B, B touches C, C touches A, D touches A, D touches B, and E touches only D. What is the smallest number of colours you need to colour the whole map so that no two touching regions share a colour?
Why this matters
Find a solution AND argue why nothing smaller can work
Take your time reading. There's no rush at all. Use the picture on the side to help it make sense, then tell me what it's really asking.