How does the reader know that Tom is actually a clever child？

How does the reader know that Tom is actually a clever child？
A.Never able to sit still， Tom craves adventure and the frontier life.
B.Tom's achievements in school are levels higher than the rest of his peers.
C.Tom's insight on human nature exceeds the understanding of other children.
D.Tom expresses deep sympathy for Aunt Polly.
正确答案：Tom's insight on human nature exceeds the understanding of other children.