According to question , we have
Delhi and Srilanka both are in Asia.

Correct Option: B

According to question , we have
Delhi and Srilanka both are in Asia.
From above it is clear that option B represents the best relationship among Delhi, Sri Lanka and Asia .As shown in given figure .

According to above given question , we know that
Doctors consists of Specialist Doctors and Patients but Specialist Doctors and Patients are of two different nature.

Correct Option: B

According to above given question , we know that
Doctors consists of Specialist Doctors and Patients but Specialist Doctors and Patients are of two different nature.
Hence , Option (B) is correct.

According to above given question , we can say that
Some guides may be philosophers and vice versa.
Some friends may be guides and vice versa.
Some friends may be philosophers and vice versa.
Some philosopher guides may be friends.

Correct Option: C

According to above given question , we can say that
Some guides may be philosophers and vice versa.
Some friends may be guides and vice versa.
Some friends may be philosophers and vice versa.
Some philosopher guides may be friends.
From above it is clear that option ( C ) gives the best relationship between Friend, Guide and Philosopher .

As we know that ,
Crows belong to class Aves. Cow is a mammal.

Correct Option: B

As we know that ,
Crows belong to class Aves. Cow is a mammal.
From above it is clear that option ( B ) represents the best relationship between Mammals, Cows and Crows .

According to above given question ,we can say that
Violinists are Instrumentalists and in turn, Instrumentalists are Musicians.

Correct Option: A

According to above given question ,we can say that
Violinists are Instrumentalists and in turn, Instrumentalists are Musicians.
From above it is clear that option ( A ) gives the best relationship between Musicians, Instrumentalists and Violinists .