What best describes index fossils? organisms that existed over a limited period . organisms whose age is hard to detect. fossils that are used in radioactive dating. fossils of the most ancient organisms.

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What is a group of organisms that are closely related and share similar characteristics

Which of these would most likely be a stimulus that would cause the body to initiate feedback mechanisms a.) normal body temperature in an arctic environment b.) normal boy temperature in a tropical environment c.)light physical activity d.)low blood sugar