The correct answer is option 4, USA. The United States of America is the world`s largest exporter of agricultural products.

Let`s analyze the other options to understand why they are not correct:

Option 1: Brazil is one of the largest exporters of agricultural products in the world, but it is not the largest. It is known for exporting commodities like soybeans, beef, poultry, and sugar.

Option 2: China is a major agricultural producer and consumer, but it is not the largest exporter. China is more focused on meeting its domestic food demand due to its large population.

Option 3: India is the second-largest producer of agricultural products in the world, but it is not the largest exporter. India primarily focuses on meeting its domestic food needs and has various challenges in exporting agricultural products.

Therefore, the correct answer remains option 4, the USA, as it is widely recognized as the world`s largest exporter of agricultural products. The USA has significant agricultural production and exports a wide range of commodities, including grains, soybeans, meat, and dairy products, to many countries around the globe.