UCEED 2019

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UCEED2019Q26·msq·Hard53 attempts

The figure shows four road networks. Which of these four road networks can be traversed by a traveller, such that the following challenge can be satisfied: 'The traveller must cover all the roads in the network. She is allowed to visit a city more than once, but she is not allowed to travel on any road more than once. Also, the traveller must come back to the city where she starts.'