The correct answer to this question is option 'C', which states that in knock-out tournaments, any team once defeated gets eliminated from the tournament. Let's explore why this is the case:

Knock-out tournaments:
- Knock-out tournaments are a popular format in sports competitions where teams or individuals compete against each other, and the losing team is eliminated from the tournament.
- These tournaments are designed to determine a single winner by gradually eliminating teams or individuals through a series of matches or rounds.

The concept of elimination:
- In knock-out tournaments, the primary objective is to identify the strongest team or individual who can consistently win matches and progress towards the final stage.
- When a team loses a match in a knock-out tournament, they are no longer eligible to continue in the competition.
- This is because knock-out tournaments follow a single-elimination format, meaning that once a team loses, they are immediately eliminated and removed from the tournament.

Reasons for elimination:
1. Ensuring fairness: Eliminating teams after a loss ensures that the tournament remains fair and competitive. It allows for a clear progression of teams based on their performance, and it ensures that only the strongest teams advance to the later stages.
2. Determining a winner: The ultimate goal of a knock-out tournament is to determine a single winner. By eliminating teams after a loss, the tournament can narrow down the field of competitors until only one team remains, which is crowned as the champion.
3. Maintaining tournament structure: Eliminating teams after a loss helps maintain the structure and integrity of the tournament. It ensures that the number of teams or participants gradually decreases as the tournament progresses, leading to more intense and high-stakes matches in the later rounds.

Conclusion:
In knock-out tournaments, any team that is defeated gets eliminated from the tournament. This elimination process is necessary to maintain fairness, determine a clear winner, and uphold the structure of the tournament. By adhering to this rule, knock-out tournaments can provide exciting and competitive matches as teams vie for the ultimate victory.