Who chooses users to be a "Top Contributor" in a specific category?

Yahoo gives it based on percentage of best answers.

this is around 12 percent in a certain category.

You can have up to 3 badges,

In 3 different categories.. thanks

It is an automatic process based on certain criteria. Giving a lot of answers with some Best Answers, in one category, gets you the TC label. You can earn up to 3 (although some seem to have 4 or 5) and Polls & Surveys and Jokes & Riddles don't have any. Rumor is 45-50 answers in one month, with 10% of them being Best Answers will do it, but I've seen it done with lots less. Updates are made on Mondays.Here is the YA Help link: http://help.yahoo.com/l/us/yahoo/answers/network/c...

You do. You choose the category and answer there for long enough and good enough and you become a TC there.