The bonus rules take effect on the fifth team foul during an NBA game quarter.
The bonus rules in the NBA take effect on the 5th team foul committed by a team in each quarter.
In an NBA game quarter, the bonus rules take effect on the team's 5th foul. This means that once a team commits their 5th foul in a quarter, the opposing team enters into a bonus situation. The bonus situation allows the fouled team to shoot free throws regardless of the type of foul committed by the defending team. So, the correct answer is 5.
