Which organism could possibly occupy the 'A' position in the food chain:

Plant → Insect → Frog → 'A' → Eagle?

Snake

The correct answer is Option (3) -Snake

Rabbit:

Rabbits are herbivores that feed on plants. They do not typically prey on frogs, so they would not fit into the given food chain in the 'A' position.

Lion:

Lions are apex predators that primarily hunt large mammals. They do not fit into this specific food chain because they do not typically prey on frogs and are not a natural prey for eagles.

Snake:

Snakes are known to prey on frogs and can be preyed upon by larger birds such as eagles. This makes the snake a suitable organism for the 'A' position in the food chain, fitting well between the frog and the eagle.

Sparrow:

Sparrows are small birds that primarily feed on seeds and insects. They are not predators of frogs, and while they can be prey for eagles, they do not fit the predator role needed for the 'A' position in this food chain.

Therefore, the snake is the correct choice because it can act as a predator to the frog and a prey to the eagle, fitting the position of 'A' in the food chain: Plant → Insect → Frog → Snake → Eagle.