Option 1 is the correct answer
Peristalsis is the involuntary relaxation and constriction of the muscles of the digestive system which causes the movement of food in the digestive system. This is actually one of the reasons why you can eat upside down, however it is not advisable.
The answer is PERISTALSIS.
A Kidney/s: They are bean-shaped organs that filter waste products and urea from the blood. The filtering units of kidneys are called nephrons. Along with water, these waste products and urea are what makes up urine.
B. Ureters - These are thin tubes that connect the kidney and bladder. From the kidneys, the urine passes through the ureter down to the bladder. These ureters are just about 8 to 10 inches long. The ureters' walls tighten and relax to prevent back flow of urine.
C. Urinary Bladder - The bladder is a hollow and balloon-shaped. It collects the urine from the ureters. The bladder is held up by ligaments that are attached to the pelvic bones and other organs. The bladder has a sphincter that prevents leakage into the end point of the urinary system.
D. Urethra - It is a tube that allows the passage of urine out of the body. Men generally have longer urethras than women. In women, the urethra is about 2 inches long and in men, about 8 inches long.
Appalachian Mountains are a part of the Lithosphere
