Clay is the least permeable type of soil. So the answer would be D-Clay
The immune system works with the digestive tract to help protect you from infection by these potential invaders. Your immune system also depends upon cells to kill invading organisms, and chemicals that don't require the involvement of cells at all, but which are simply toxic to bacteria and viruses. Acid in the stomach does the same thing.
That body parts are called "Homologous Organs" which are similar in origin & structure.
Hope this helps!
