Consider the following claim about positive integers $a$, $b$ and $c$: > *if* $a$ is a factor of $bc$, *then* $a$ is a factor of $b$ *or* $a$ is a factor of $c$

Which of the following provide(s) a counterexample to this claim?

I $a=5,b=10,c=20$

II $a=8,b=4,c=4$

III $a=6,b=7,c=12$

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