I believe it should match as the following...
sight in whales -----> eyeballs in cavefish
balance in monkeys -----> tailbone in humans
attachment point for limbs in frogs -----> pelvis bone in whales
This is a law because it is based on observations (Newton's Third Law)
Answer:
One snail for two plants.
Explanation:
One snail and two plants we need to keep a stable environment because the snails help to clean up garden debris by feeding on them and their feaces has nitrogenous nature which is nutritive for the plants. So the plants get nutrients from the snail as well as carbondioxide gas used by the plants for the process of photosynthesis. So we can say that snails are important for maintaining a stable environment.
Homologous structures are structures (body parts/anatomy)
which are similar in different species because the species have common descent.
They may or may not perform the same function. An example of homologous
structures is the forelimb structure shared by cats and whales.