Two populations of organisms belong to the same biological species when they
A. can't mate with each other, because mating occurs at different times.
B. use different types of behaviors or physical features to attract mates.
C. have anatomical features that make it difficult for organisms from the different populations to mate.
D. encounter each other, mate, and produce viable, fertile offspring under natural conditions.
Answer:D
Two populations of organisms belong to the same biological species when they
A. can't mate with each other, because mating occurs at different times. B. use different types of behaviors or physical features to attract mates. C. have anatomical features that make it difficult for organisms from the different populations to mate. D. encounter each other, mate, and produce viable, fertile offspring under natural conditions.