In a hockey championship, there are 153 matches played. Every two team played one match with each other. The number of teams participating in the championship is:

Answer: Option C

Let there were x teams participating in the games, then total number of matches,
ⁿC₂ = 153
On solving we get,
⇒ n = −17 and n =18
It cannot be negative so,
n = 18 is the answer.