Which soil cannot be rolled into balls or clumps

Your answer would be Sand.

If you go to the beach, and try making balls in your hand it's nearly impossible. If you pick up sand it will just fall through the crevice's in your hand, or a simple movement of your hand can make the sand fall. Sand simply can't be formed into a ball.

If you where to try making a ball of sand the outcome wouldn't be great. Even if you made the sand damp you still can't really make a ball of sand.

straight or amphibians are homeothermic to thermal

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.