In the following diagram, the triangle represents the students who want to have Dosa in their lunch. The rectangle represents the students who want to have a sandwich in their lunch. The circle represents the students who want to have pizza in their lunch. The square represents the students who want to have Idli in their lunch. The hexagon represents those students who want to have Puri Sabji at the time of lunch.

How many students want to have Dosa, sandwich, and pizza, all three in their lunch?

Logic: To determine the number of students who want to have Dosa, sandwich, and pizza in their lunch, get the number that is common in the regions of dosa, sandwich, and pizza. In the below diagram, the shaded part represents the required region.

So, there are 25 students who want to have a dosa, sandwich, and pizza.

Thus, the correct answer is (d).