Answer:
Symbiosis is a close relationship between two species in which at least one species benefits.
Explanation:
Answer:
A
variations in the population
Answer: Gastroenterology
Explanation: Gastroenterology is a branch of medicine concerned with digestive diseases. The practice of gastroenterology concentrates on the diagnosis and treatment of diseases involving the esophagus, stomach, small intestine, and large intestine (colon), liver, and pancreas. Examples of conditions treated: Abdominal pain.