In a taxonomic diagram, if the organism at location D is the most recent common ancestor to the organisms at locations A, B, and C, what is the relationship of organism D to A, B, and C?

• A. Organism D is the common ancestor of organisms A, B, and C.
• B. Organism D is a sister species to organisms A, B, and C.
• C. Organism D is a descendant of organisms A, B, and C.
• D. Organism D is unrelated to organisms A, B, and C.

Answer: (A)

Verified step by step guidance

1. Understand the concept of a 'common ancestor' in taxonomy. A common ancestor is an organism from which two or more descendant species have evolved. It represents a shared lineage in a phylogenetic tree.
2. Examine the taxonomic diagram. If organism D is identified as the most recent common ancestor of organisms A, B, and C, it means that D is the point in the evolutionary tree where the lineages of A, B, and C diverged.
3. Clarify the relationship between organism D and organisms A, B, and C. Since D is the ancestor, it cannot be a descendant or a sister species to A, B, and C. A sister species would share a common ancestor with A, B, and C but would not be the ancestor itself.
4. Eliminate incorrect options based on the definition of a common ancestor. Organism D cannot be unrelated to A, B, and C because it is explicitly stated to be their common ancestor.
5. Conclude that the correct relationship is: Organism D is the common ancestor of organisms A, B, and C. This aligns with the definition of a common ancestor in evolutionary biology.