Concept:Agriculture mainly ensures food supply, employment, and raw materials for industries, but earning foreign exchange is only an additional benefit.
Explanation:Agriculture supplies raw materials to agro-based industries, such as cotton to textile mills and palm oil to food-processing factories.
It provides jobs for many people, especially those in rural and farming communities.
It supplies food for human consumption and animal feed, thereby ensuring food security.
Agriculture can earn foreign exchange through the export of cash crops.
However, it is not always the main source of foreign exchange for a country.
Many countries depend more on oil, gas, manufacturing, or service industries for their main foreign exchange earnings.
Therefore, describing agriculture as the main source of foreign exchange is not generally correct.
Answer:Option B: serving as main source of foreign exchange.