Which is an example of a chemical change that occurs during weathering? A. freezing and thawing of water in the cracks of rocks
B. Animals dig a hole in the ground looking for worms
C. flowing water smooths rock surfaces in a river
D. Acids from the lichens growing on the rock breaks down the rock to soil

d the acid changes the chemical composition in the contents of the rock

Explanation:

i need an image of the diagram

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.