Concept:
Gender refers to socially and culturally defined roles, behaviours, and expectations associated with men and women.
Step 1:
Gender is different from biological sex because it is shaped by society and culture.
Step 2:
A social construction is something created and maintained through social interaction and cultural practices.
Step 3:
Ideas about masculinity and femininity vary across societies and time periods, showing that gender is socially constructed.
Step 4:
• Biological and physiological constructions relate more closely to sex differences.
• Educational construction is not the accepted sociological concept here.
Step 5:
Hence, the correct answer is Social Construction.
\[
\boxed{\text{(3) Social Construction}}
\]