If there are two white balls, then there must be three red balls (rule 1) and one green ball – you always need a green ball.
Since there’s only one green ball, there must be a white ball directly in front of it (rule 2). And this WG pair must be in front of all red balls (rule 3):
There is a second white ball. This is the only ball that can go in front of the WG pair. So green can go second or third:
B is CORRECT.
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