The correct answer would be D. Mollusca.
The question is basically describing a snail.
Arthropoda have segmented bodies.
Echinodermata(starfishes, sand dollars etc.) are radially symmetrical.
Also none of them have shells except phylum Mollusca :)
Answer: the mantle B
Explanation: Largest layer resulting in biggest mass.
You just have to describe on how the cell structure will describe themselves .
The pond will continue to get smaller and posibly will not exist at all. The area will be covered in shrubs because the dirt had softened because of the water. I think this might be the answer or something like it. Hope this helps!
B double helixxxxxxxxxxxx
