Step 1: Understanding the Concept:
Measuring socio-demographic indicators like educational levels and gender-based differences helps analyze the developmental trajectory of a country's population.
Comparing overall national literacy progress with gender-specific metrics provides a clear understanding of systemic educational shifts.
Step 2: Detailed Explanation:
Assertion (A) states that India has experienced a major rise in overall educational levels over the past three decades.
This is supported by national census data.
India's overall literacy rate grew from approximately \( 52.2\% \) in 1991 to over \( 77.7\% \) in recent surveys.
Primary, secondary, and higher education enrollment numbers have also risen substantially.
Therefore, Assertion (A) is correct.
Reason (R) states that gender disparities in educational attainment have narrowed during this same period.
This is also correct.
Due to targeted government programs like Sarva Shiksha Abhiyan and Beti Bachao Beti Padhao, female literacy rates have improved at a faster relative rate than male literacy rates.
The gender gap in literacy shrunk from nearly \( 24.8\% \) in 1991 to about \( 14.4\% \) in recent assessments.
Importantly, the shrinkage of this gender gap directly explains the broader increase in overall national educational levels.
Since females make up nearly half the population, major progress in national education is structurally impossible without closing gender disparities in school enrollment and literacy.
Thus, both (A) and (R) are correct, and (R) is the direct explanation of (A).
Step 3: Final Answer:
The correct option is (A).