Rani ranks 9th from the top while Ravi ranks 19th from the bottom in an exam…

When a person's rank is known from both the top and the bottom of the same ranked list, the total number of people in the list equals (rank from the top) + (rank from the bottom) minus 1 -- the minus 1 removes that person's own position, which both end-ranks count once.

1. Rani ranks 9th from the top.

2. Exactly one rank lies between Rani and Ravi, so their positions from the top differ by two places. That leaves two mathematically possible positions for Ravi: 11th from the top (if Ravi ranks below Rani) or 7th from the top (if Ravi ranks above Rani).

3. Ravi is also given as 19th from the bottom. Applying the total-count formula to each possibility: taking Ravi as 11th from the top gives Total = 11 + 19 - 1 = 29; taking Ravi as 7th from the top gives Total = 7 + 19 - 1 = 25.

4. Only 29 appears among the answer choices offered for this question, so 29 is the total consistent with the choices given here.

Check the chosen total: with 29 students, Rani's rank from the bottom = 29 - 9 + 1 = 21, and Ravi's rank from the top = 29 - 19 + 1 = 11. The ranks from the top are then 9 (Rani) and 11 (Ravi) -- exactly one rank (the 10th) lies between them, matching the given condition.

So the list contains 29 students.