Answer:
The two correct answers are the first and the third.
Explanation:
Kate and Sue are not the same age. This is evidenced by Kate being described as the oldest and Sue being described as the youngest. Therefore, the second revision does not make sense because it refers to them BOTH being eight at the same time, which is incorrect as we are led to believe they are different ages. The fourth answer does not make sense because the "we" implies that the speaker, Kate, and Sue are all the same age, which is also incorrect as it assumes once again that Kate and sue are both eight simultaneously in addition to the speaker, of whose age we have no knowledge and thus cannot assume.
Therefore, the two correct answers are the first and the third. In each of these, it is specified who exactly is eight at the given time, which is the clarification the question asks for.