13. Which statement about the aquaculture industry in the US is true? O A. Most commercial salmon farms raise Pacific salmon.
O B. Salmon comprise the largest segment of aquaculture in the US.
O C. Interest in aquaculture has been increasing.
O D. Most trout are raised in the South.

a "theory" a suggestion that is not 100 % accurate, or a figure. some people say its a theory because they of all the passed theory's about one subject. it depends sometimes theory might be accurate and sometimes they are.

it's diluted or concentrated

in a diluted solution, you can add a lot more solute but in concentrated only a little more can be added