The observation for the student #2 must starts by the claim, going to evidence, and finishing with the reasoning.
1 - Claim = To the grass (producer) is easier to acquire nergy than it is for a hawk (quartenary consumer), because the base of the food pyramid is where most of the energy of the food chain is maintained, and the producers are able to produce their own food from the natural resources in the environment;
2 - Evidence = The food web in the picture shows how the trophic levels are distribute in the ecosystem, being the food pyramid divided into: producers (autotroph organisms), consumers (primary-herbivores, secondary-omnivore, and tertiary-carnivore), predators, preys, and decomposers. The graph shows that from each levels a small quantity of energy is lost by the organisms, going from the levels with more energy (plants- that uses the sun to make photosynthesis) until the tertiary consumer (the pradator - hawk, that is a heterotroph). To have energy the plants need only to be in a good place, while the hawk have to go after preys and an environment that have a good balance between the trophic levels;
3 - Reasoning = The student #2 came to the conclusion that is much difficult for the hawk to obtain energy because of the observation of the challenges for each level tropic level being bigger and bigger. That's because the way that each organism get their food and what it eats is a determinant factor, as well the loss of energy to complete the most basic functions. Being the conclusion that the grass that just need sunlight and water have a lot less difficults and energy loss than a hawk that needs to hunt for food, survival, reprodutive needs and so on.