Which of the following is an example of a biological system? a. biology textbook b. the universe c. human digestive tract d. a car engine

Option C. "Human Digestive Tract"

Explanation:

Biological system is a network of living organism interact with each in a manner to maintain balance in the system.

Humans cover major part of biological system. The human digestive system is an important part of human body that consist of gastrointestinal tract along with the tongue, salivary glands, pancreas, liver, and gallbladder.

Human digestive tract or system functions in digestion of food that is responsible to provide energy to the body.

Biology textbook , the universe, and car engine are all non living organs.

Hence, human digestive tract is an example of biological system.

the abdomen (less formally called the belly, stomach, tummy or midriff) constitutes the part of the body between the thorax (chest) and pelvis, in humans and in other vertebrates. the region occupied by the abdomen is termed the abdominal cavity. the stomach secretes acid and enzymes that digest food. ridges of muscle tissue called rugae line the stomach. the stomach muscles contract periodically, churning food to enhance digestion. the pyloric sphincter is a muscular valve that opens to allow food to pass from the stomach to the small intestine.

mountains can affect the climate of nearby lands. in some areas, mountains block rain, so that one side of a mountain range may be rainy and the other side may be a desert. much of airborne moisture falls as rain on the windward side of mountains.

explanation: