In the present structure of India's economy, which sector contributes the largest share to the country's national income?

Introduction / Context:
Over the decades since independence, India has moved from being a primarily agrarian economy to a more diversified one. Today, different sectors contribute differently to national income, employment, and exports. This question tests awareness of which broad sector currently provides the main share of national income. Knowing this helps students understand structural change in the Indian economy and interpret government statistics and policy documents correctly.

Given Data / Assumptions:

• The focus is on the present structure of India's economy, not the situation immediately after independence.
• The question asks about the largest contribution to national income, not to employment.
• Options include the service sector, agriculture sector, industrial sector, trade and commerce sector, and construction sector.
• We assume recent national accounts where services have grown significantly.

Concept / Approach:
In many developing economies, agriculture initially dominates national income, followed by industrialisation and later by growth of services. In India, after economic reforms and rapid urbanisation, the service sector expanded strongly, including trade, transport, communications, banking, insurance, information technology, tourism, and various professional services. Today, services contribute well over half of India's gross domestic product, while agriculture's share has fallen and industry remains important but smaller than services. Therefore, when asked which sector is the main source of national income in India, the correct answer is the service sector.

Step-by-Step Solution:
Step 1: Recall that agriculture once formed a large share of national income but its percentage has declined over time as the economy diversified. Step 2: Note that industrial activity, including manufacturing and mining, grew but did not overtake services in terms of share of gross domestic product. Step 3: Observe that modern statistics show a strong dominance of services, often contributing more than half of national income. Step 4: Recognise that trade, commerce, finance, information technology, and many other service activities fall under the service sector classification. Step 5: Conclude that the service sector is the main source of national income in India.

Verification / Alternative check:
Students can confirm this by looking at any recent Economic Survey of India or standard Indian economy texts. Charts showing sectoral shares of gross domestic product clearly place services at the top, with industry and agriculture following. Even though agriculture may still employ a large portion of the workforce, its share in income is smaller. This pattern of a service led economy is also commonly discussed in news analyses of India's growth story, especially regarding information technology and business process outsourcing.

Why Other Options Are Wrong:
The agriculture sector once dominated the economy but its share in gross domestic product has decreased significantly, so it no longer contributes the largest portion of national income.
The industrial sector is important for manufacturing and infrastructure, yet its contribution in value terms is still lower than that of services.
Trade and commerce are major components of the service sector, not a separate highest level sector in standard classifications, so they cannot represent the largest share by themselves.
The construction sector, while growing due to urbanisation and infrastructure development, contributes a smaller share compared with the broad and diverse service sector.

Common Pitfalls:
Many learners associate the term developing country with an agriculture dominated economy and may automatically choose agriculture as the main source of national income. Another pitfall is to confuse employment share with income share; agriculture employs many people but produces a lower proportion of total value. To answer such questions correctly, students should focus on sectoral contribution to gross domestic product, where the service sector now clearly leads.

Final Answer:
In the current structure of India's economy, the service sector contributes the largest share to national income.