"A" I think... Sorry if its not right...
Answer:
if sex cells were identical, there won't be genetics variations and we will just all be identical to our parents. genetic variation allows us to better adapt and survive
There is much more fresh water underground than on the surface. A rock layer must be porous and permeable to be a good aquifer. An impermeable layer makes up the bottom of an aquifer. The water table rises and falls with additions or subtractions to the groundwater system.
2. Egg cells!
Hope this helped you out!
ALL animals make use of other animals and organisms for food. They are heterotrophic so they have to get energy elsewhere.
ALL animals are capable of motion at some stage of their lives.
Animals developed specialized cells and tissues that are advanced and complex.
And because all animals eat I would assume they all digest the food they ingest. Other than parasites who don't really digest their food.