This is a symbiotic relationship between the Boxer crab and sea anemone.
<h3><u>Explanation</u>:</h3>
The symbiosis is a type of relationship between two species which has benifit for both the participating organisms.
Here in case of boxer crab, the crab gets the help from the sea anemone in the form of protection. The sea anemone chases the predators and thereby saves the organism from being hunted.
On the other hand, the sea anemone gets food from the crab's prey which he hunts.
So there's a benifit for both.
The correct answer is A. Hope this helps! ;)
Regulating pollutant discharges into the waters of the United States
-Surface area to volume ratio. (surface area / volume)
-Nucleo-cytoplasmic ratio.
-Fragility of cell membrane.
-Mechanical structures necessary to hold the cell together (and the contents of the cell in place)