21. A Stale Fish has the following specific characteristics except one: a. Discoloration which is a discernible abnormal color changes in some parts characterized by varying degrees of spoilage. b. The milky slime in stale fish appears cloudy white and is slightly transparent. c. The eyes are considered slightly sunken if the eyes are not bulging, or are slightly depressed d. A fresh fish with intact belly walls have no protruding viscera and the walls are not ruptured but firm and springy. 22. What is the main concern of fish processing?​