Where does “boo” come from?

I need to work through this carefully. The chain given is: English beau → French beau → Latin bellus → Latin bonus → Latin bellus → Latin bellus → Latin bonus → Proto-Indo-European deu- However, the headword I'm asked to write about is "boo" (English), not "beau." This appears to be a mismatch. The chain provided traces "beau," but I'm being asked to write the origin summary for "boo." These are different words with different etymologies. Additionally, the chain as presented is problematic: it shows Latin bellus and bonus appearing multiple times in sequence, which suggests either corruption in the data or a misunderstanding of the chain format. Given that the instructions state "State only what the chain supports. Do not invent dates, cognates, or intermediate steps," I cannot reliably write a summary for "boo" based on a chain that

boo (English): A loud exclamation intended to scare someone,...