Answer:
1.Finneas, who was tall for his age, loomed over Quentin.
Explanation:
commas are used to separate additional information in a sentence. For example the sentence would still be valid if you say "Finneas loomed over Quentin. But you want to add that finneas was taller than quentin hence the need to put commas over the information you add.
In the second sentence, if you say "Finneas who was tall for his age over Quentin. You lose the meaning of the sentence.
