A'ring' is simply a chain or part of a molecule where the atoms form into a circle ring. these amino acids have rings in their sidechains: tryptophan answer 1 phenylalanine answer 2 arginine answer 3 histidine answer 4 methionine answer 5 glutamic acid

The amino acids with rings in their sidechains are tryptophan, phenylalanine, and histidine (see the attached image).

Arginine methionine, and glutamic acid do not have rings in their sidechains.

a  solution  is always transparent, light passes through with no scattering from solute particles which are molecule in size. the  solution  is homogeneous and does not settle out. a colloid is intermediate between asolution  and a  suspension. while asuspension  will separate out a colloid will not.