Let us denote the students as:
- Rishi (R): Class 5, boy
- Swathi (S): Class 5, girl
- Pavan (P): Class 4, boy
- Tanvi (T): Class 4, girl
A player who loses a game is eliminated permanently, so after 3 games there is exactly one student who never loses.
We use the conditions one by one.
Step 1: The first game must be the only same-class game
If the first game were between the Class 4 students (P vs T), then after one of them loses, the remaining three students would be:
- one Class 4 student
- both Class 5 students
Now the last two games must both be cross-class. But after one cross-class game among these three, the loser is eliminated, leaving either:
- two Class 5 students, or
- two Class 4 students
That would force the third game to be a same-class game, violating condition (i).
So the first game cannot be P vs T.
Hence the first game must be between the Class 5 students:
R vs S.
Step 2: Who wins the first game?
Suppose Swathi wins the first game. Then the winners so far are:
- one Class 5 win
- one girl win
The remaining players are S, P, T, and the next two games must both be cross-class.
To satisfy condition (ii), Class 5 must win more games than Class 4, so Swathi would need to win at least one more game.
But then girls would have at least two wins, contradicting condition (iii), which says:
- boys won exactly 2 games
- girls won exactly 1 game
Therefore, Swathi cannot win the first game.
So the first game must be won by Rishi.
Step 3: Determine the next two games
After Rishi beats Swathi, the active players are:
R, P, T.
The second game must be cross-class.
- If Rishi loses the second game, then the remaining two players would be P and T, both from Class 4, so the third game would again be a same-class game. Not allowed.
- Therefore, Rishi must also win the second game.
So the second game must be:
R beats P
because if R beat T instead, the remaining players would be R and P, and Rishi would then also win the third game, giving boys all 3 wins, which violates condition (iii).
Now only Rishi and Tanvi remain for the third game, and Tanvi must win it.
So the unique valid sequence is:
- Rishi beats Swathi
- Rishi beats Pavan
- Tanvi beats Rishi
The student who never lost any game is therefore Tanvi.
Therefore, the correct answer is Option D.