In basketball, when a referee throws the ball up in the center circle to determine which team gets the ball, it is called a _________.

The correct option is Jump ball.

Explanation:
In basketball, a game officially begins with a jump ball in the center circle. The referee tosses the basketball vertically into the air between two opposing players (usually the centers), who jump up to tap the ball toward their respective teammates to gain initial possession of the ball.

Analysis of the options:
• Jump ball: Correct. This is the official term for tossing the ball up in the center circle to start play or resolve a held ball situation.
• Dunk ball: Incorrect. A slam dunk is an offensive shot where a player jumps up and throws the ball directly downward into the basket.
• Hook ball: Incorrect. A hook shot is a specific basketball shooting technique where a player sweeps their arm over their head in a curved motion.
• High ball: Incorrect. This is not a standard basketball term for determining possession or starting play.