Each of the 9 segments in the figure is to be coloured either blue, green or red.

The sides of every triangle are to be different colours.

Three of the segments have already been coloured, as shown.

Question:

What colour can the segment marked with \(x\) be?

\(\text{only blue}\)\(\text{only green}\)\(\text{only red}\)\(\text{either blue, green or red}\)\(\text{such a colouring is not possible}\)