Answer:
B. When he remembered his first summer at camp, Taiyo
smiled. He had first met his friend Marco there. Marco
was the best friend a person could ever ask for, and
Taiyo felt lucky.
Step-by-step explanation:
This is about the use of commas. It's kind of complicated, but if you read enough you'll just be able to tell if a sentence looks right or wrong.
A has way too many commas.
There is nothing glaringly wrong with B.
C is way too choppy. Remember we're trying to find the answer that enhances the flow and writing style of the story. All the sentences are so short and none of them lead to the next one. Where's the flow?
D also has too many commas. It makes the second sentence too long.
I hope this helps :)