Option 2, "Grass - Rabbit - Fox," is the grazing food chain. A grazing food chain starts with producers, which in this case is grass. The herbivores, such as rabbits, consume the producers, and then the carnivores, in this case, foxes, feed on the herbivores. This sequence represents the flow of energy from one organism to another. Option 1, "Dead animal - Maggots - Frog - Snake," does not represent a grazing food chain as it includes decomposers (maggots) and predators (frog and snake), but not a primary producer like grass. Option 3, "Trees - Fruits eating birds - Lice and bugs," involves fruit-eating birds and the insects they consume, but it does not involve grazing on plants. Therefore, option 2 is the correct answer.