If the triangle represents doctors, the circle represents teachers and the rectangle represents film-makers in the following diagram

Then which numbers represent teachers who are neither doctors nor film-makers ?

We want teachers (elements that are part of the circle), but those who are not Doctors (part of the triangle), and not filmmakers (part of the rectangle). 

2, 5, 7, and 3 are part of the circle, and hence are the teachers. 

7 is a teacher and a doctor, and hence should not be considered. 

3 is a teacher and a filmmaker, and would also be eliminated. 

Leaving only 2 and 5 that satisfy our condition. 

Therefore, Option D is the correct answer.