Step 1: Understand the question.
The question asks to identify the sector that contributes the highest percentage to the Gross Domestic Product (GDP) of Chhattisgarh. This requires specific knowledge of the economic structure of the state.
Step 2: Analyze Chhattisgarh's unique economic profile.
Chhattisgarh is a state in India particularly known for its rich natural resources, especially minerals like coal, iron ore, and limestone. This abundance has led to the development of robust heavy industries, including steel, cement, and power generation. While agriculture is a significant traditional sector and services are growing, the state's industrial base is a defining characteristic of its economy.
Step 3: Determine the dominant sector based on GSDP contribution.
Unlike the national trend where the services sector dominates, in resource-rich and industrially focused states like Chhattisgarh, the Manufacturing (Industries) sector often holds the largest share of the Gross State Domestic Product (GSDP). This includes contributions from mining and quarrying, manufacturing, electricity, gas, water supply, and other utility services, as well as construction. Given Chhattisgarh's strong base in steel, aluminum, cement, and power, the industrial sector (which encompasses manufacturing) becomes the primary driver of its economy.
Step 4: Evaluate the given options.
Option (1) Agriculture: While important for employment and rural economy, its contribution to GSDP is generally less than the industrial or services sector in industrially developed states.
Option (2) Manufacturing (Industries): This is the correct answer. Chhattisgarh's economy is heavily reliant on its mineral wealth and the industries built upon it, such as steel, cement, and power.
These industrial activities, including manufacturing and mining, typically form the largest share of the state's GSDP.
Option (3) Services: While the services sector is growing in Chhattisgarh, it typically holds the second-largest share after industries, or sometimes a close third, depending on the specific year's data, but generally not the largest.
Option (4) All equally: This is incorrect, as economic contributions from different sectors are rarely equal.
Step 5: Conclude based on the specific economic structure of Chhattisgarh.
Chhattisgarh's economy is distinct in that its vast mineral resources and associated heavy industries significantly boost its manufacturing/industrial sector, making it the largest contributor to the state's GDP.
The final answer is $\boxed{\text{2}}$.