[Solved] Which of the following principles underlies the interaction of individual choices? A)Resources are scarce. B)There are gains from trade. C)Marginal analysis is used for "how much" decisions. D)People usually exploit opportunities to make themselves better off. Ammonia: A colorless gas with a distinct sharp smell, commonly used in cleaning products and as a fertilizer, and also produced naturally in the human body. Bacteria: Microscopic, single-celled organisms found everywhere in the environment, which can be either beneficial or harmful to humans and other living beings. Occult Blood: Blood not visible to the naked eye, often detected in stool or urine samples to diagnose conditions such as gastrointestinal bleeding. Colon Cancer: A type of cancer that begins in the large intestine (colon), often detected through screening methods like colonoscopies.