What is the function of the waxy, transport top layer of leaves ?

The layer should be the waxy cuticle, and its function is mainly to reduce water loss by evaporation from the leaves.

That's why the stem of a cactus is waxy, this is because the layer can prevent the cactus from losing too much water, especially when the cactus is usually found in desert area where water is not always available.

The waxy cuticle is mostly found only on the top of the leaves, this is because sunlight shines directly to the top of the leaf instead of the bottom of leaf, plus, there are stomata at the bottom of leaves, which is like pores for water loss of the plant and carbon dioxide absorption, which is necessary for photosynthesis.

the two answers are a, the population of birds with large beaks will increase on the island, and c, the trait for large beaks will be passed on to future generations through natural selection. the reason for that is because if the birds that have beaks developed for eating small seeds lose all of their food, they will go hungry and eventually starve because they physically cannot eat the large seeds, therefore making the population of large beaked birds higher. also, if the trait of large beaks are dominant on the island over small beaks, then over time the large beaked birds will reproduce more and more, while the smaller beaked birds will reproduce less and less because they can't survive with the food provided. that leads to the trait of small beaks disappearing and the trait of large beaks taking over the island.