The moray eel and grouper fish hunt together. When both hunt together, prey barely stands a chance: hide in the reef, the eel eats you; dash for open water, the grouper grabs you. Which symbiotic relationship is described above? A. Coevolution
b. Mutualism
c. Parasitism
d. Commensalism​

We can immediately cross-out C

We can also cross-out  A.

Now we have B and D.  Commensalism and Mutualism. Now, commensalism is an association between two organisms in which one benefits and the other derives neither benefit nor harm.

Mutualism is the doctrine that mutual dependence is necessary to social well-being.

I would say D: Commensalism​. Both fish can survive without each other.  

there is not 1 highest source of protein, but there are many; meats, fish, poultry, seafood, cheese, eggs, yogurt and milk. the only non complete animal food that is beneficial is gelatin.

sorry if this did not , have a great day!