Final answer:
Bud remains silent about the beating from Todd Amos because he fears the adults will not believe an orphan over their own son and aims to protect himself from further harm.
Step-by-step explanation:
In the novel Bud, Not Buddy by Christopher Paul Curtis, Bud Caldwell does not tell the truth about Todd Amos beating him up because he fears the adults will not believe him. Bud has experienced the harsh realities of the Great Depression era's foster system, where adults often dismiss the words of children, especially orphans like himself. He understands that the power dynamics are not in his favor and believes his word will not stand against Todd's, who is the biological son of the Amos family. Bud's silence also reflects his coping mechanism of avoiding further trouble and protecting himself from more harm.