The correct answer is option 1: Agriculture and allied activities. This sector in India has the highest share of employment.

Agriculture and allied activities refer to the cultivation of crops, rearing of livestock, forestry, and fishing. In India, a significant portion of the population is engaged in agriculture as their primary occupation. This sector provides employment to a large number of individuals, especially in rural areas.

Option 2: Manufacturing is the sector involved in the production of goods through the use of machinery, tools, and labor. While manufacturing also contributes to employment in India, it does not have as high a share of employment as agriculture.

Option 3: Construction refers to the building and development of infrastructure, such as roads, buildings, and bridges. While construction does provide employment opportunities, it is not the sector with the highest share of employment in India.

Option 4: The tertiary sector, also known as the service sector, encompasses activities such as trade, transport, communication, finance, and healthcare. While the tertiary sector is growing rapidly in India, it does not have the highest share of employment compared to agriculture.

Therefore, option 1 (Agriculture and allied activities) is the correct answer as it has the highest share of employment in India.