In a food chain, organisms are arranged in a linear sequence based on who eats whom. In option 1, the organisms listed are grass, human, and fish. While it is true that humans can eat fish, there is no direct connection between grass and fish, so they do not form a food chain together.

Option 2 consists of grass, goat, and human. This grouping does form a food chain. Grass is eaten by goats, and goats are consumed by humans. Therefore, option 2 is the correct answer.

In option 3, the organisms listed are a tree, tree cutter, and tiger. Although a tiger could potentially eat a tree cutter, there is no natural connection between a tree and a tiger, so they do not form a food chain together.

Option 4 includes a goat, cow, and human. While it is true that humans can consume both goats and cows, there is no direct connection between goats and cows, so they do not form a food chain together.

Overall, option 2, which includes grass, goat, and human, is the only group of organisms that forms a food chain.