All of the following are examples of secondary sources except:
a. a biography of otto von bismarck
b. a letter from a soldier who fought in the napoleonic wars
c. a world history textbook
d. a dvd on the battle of normandy

answer: 20 percent

the fish culture has become a developing commercial practice in developing countries which is already prominent in developed countries of the world. the major fish protein demand is being supplemented in developing countries is   fishing to meet the needs of the growing population. therefore, in some developing nations, the percentage of animal protein from fish in the diet can be as high as 20 percent.