Venn Diagram 1

[C] is the right answer because the question is only married trained nurses, so the diagram circle, triangle (represents nurses in hospital) and rectangle where intersect is the married trained nurses to the hospital. So the answer is 5 only.

This is because in the given data states that there are only married, trained nurses in the hospital. But in the question it is asked as whether the nurse is unmarried. Eventually, the answer should be the left out number (the number in the triangle&square). So the answer is 4 only.

Option A = 3, 6 ; Here 3 is 'just only a married population'.
Option B = 7, 5 ; Here 7 is 'married nurses in hospital but not trained'.
Option D = 1, 1 ; Here 1 is 'nurses in hospital but not trained'.

But, Option C = 5, 6 ; Here both 5 & 6 are covered with 'Trained nurses'. Hence the required answers.

3 people married but not in hospital and 1person is not trained but in the hospital so if we exclude 3 and 1 from the assumptions only 7are in a hospital who are married and untrained.

As triangle represents the nurses in hospital.

And circle represents the married population.

7 is in intersecting point of circle and triangle

So, No 7 repersents mazrried nurses in the hospital.