Why was jefferson chosen as the primary writer of the declaration of independence?

It was decided by a group that each member would vote their choice. Jefferson came in first and Adams second. 

-https://www.varsitytutors.com/earlyamerica/freedom-documents/asked-jefferson-write-first-draft-decla...

Delegates: representatives who cast votes at a political party's national convention. binding: if a primary or caucus is “binding” that means the delegates won in that contest are legally bound to vote for a particular candidate at the parties national convention.a primary is a preliminary election used to determine a party's nominee for a specific office. the winner of the party's caucus, or primary, wins the party nomination for that state. then the delegates meet at their party's national party convention, which is a formal gathering of all party delegates from all states.