Explain simply why March 7 is the correct answer to: Passage: The 2018 Phillips 66 Big 12 Men's Basketball Tournament was a postseason men's basketball tournament for the Big 12 Conference. It was played from March 7 to 10, in Kansas City, Missouri at the Sprint Center. Kansas defeated West Virginia in the championship game to win the tournament and receive the conference's automatic bid to the NCAA Tournament.

Question: Based on this passage, when does the big 12 men's tournament start?. Explanation:
The important part for answering this question is: It was played from March 7 to 10, in Kansas City, Missouri at the Sprint Center.