In some type of pressure, such as gravity or blood pressure, forces substances across a membrane that acts like a filter.

In FILTRATION, some type of pressure, such as gravity or blood pressure, forces substances across a membrane that acts like a filter.
Filtration

Urea is the cellular waste product that the kidneys remove from the blood.Kidneys are the two bean shaped organs that has several functions to keep the body healthy. It not only removes urea from the blood, but also helps in the formation of urine and maintaining the fluid level of the body. The two kidneys are placed on the two sides of the spinal cord. The blood enters the kidney through the renal artery. The nephron within the kidneys mainly take out the waste products and the excess water from the blood and purifies it.If the kidneys of a person fail to work properly then it becomes important to perform dialysis for taking out the waste materials from the blood.

Of the cold they can survive in the cold

The answer would be d. pili