In a Venn diagram consisting of a rectangle, a circle, and a triangle, if the region enclosed by both the rectangle and the circle but not by the triangle is labeled with a specific number, and that number is 4, which option correctly identifies this value?

In a certain Venn diagram representing professional and demographic categories, if a triangle represents doctors, a rectangle represents women, and a circle represents postgraduates, which region representing the intersection of all three shapes gives the total number of postgraduate female doctors as 15?

In a Venn diagram, a Rectangle stands for 'Mathematics', a Circle stands for 'Teachers', and a Pentagon stands for 'Physics'. The numbers in the region represent the number of persons in that particular category. Which region represents the number of Teachers who teach Physics only?