Answer:
Jake, who is the luckiest guy I know, won the raffle prize.
Step-by-step explanation:
Alright so I don't really know how to explain this well, but I'll try. Basically, the second one is wrong because of...ugh, I don't know how to explain this. It's more like- separation. Jake is the topic of the sentence. That needs a comma. "Jake, who is the luckiest guy I know," that underlined part would need a comma to separate that from Jake's name. Then "won the raffle prize" wouldn't need a comma, as that's what Jake did. I probably messed up that explanation, but I hope this helps.