Choose the Venn diagram which best illustrates the three given classes: Diseases,leprosy,scurvy.

Choose the Venn diagram which best illustrates the three given classes: Sun,Moon,Stars.

Choose the Venn diagram which best illustrates the three given classes: Atmosphere,Hydrogen,Oxygen.

Select from the four alternative diagrams,the one that best illustrates the relationship among the three classes: pigeons,birds,dogs.

Choose the Venn diagram which best illustrates the three given classes: Yak,Zebra,Bear.

In the given diagram,circle $A$ represents teachers who can teach Physics,circle $B$ represents teachers who can teach Chemistry,and circle $C$ represents those who can teach Mathematics. Among the regions marked $p, q, r, s, t, u, v$,the one which represents teachers who can teach Physics and Mathematics but not Chemistry is: