Concept:
Sociology studies human society, social behaviour, institutions, and interactions.
Step 1:
Sociologists are interested in all forms of social behaviour and social relationships.
\[
A \text{ is correct}
\]
Step 2:
The subject examines family, religion, education, politics, economy, culture, and social change.
Step 3:
The statement about philosophy focusing on economic and physical resources is incorrect.
\[
R \text{ is incorrect}
\]
Step 4:
Economics mainly studies economic resources and development, whereas philosophy studies ideas, logic, and values.
Step 5:
Therefore, Assertion is correct but Reason is incorrect.
\[
\boxed{\text{(3) (A) is correct but (R) is not correct}}
\]