Given the task definition and input, reply with output. In this task, you are given two facts, and a multiple-choice question. Based on the given facts, answer the question with index of the correct option (e.g, "A").

Fact1: Phylogeny is the evolutionary history of a group of related organisms., Fact2: Metazoan phylogeny Phylogeny of phyla is poorly understood., Question: What is poorly understood for metazoas? (A) habitat (B) antigens that cause allergy (C) intervertebrate (D) evolutionary history (E) protein foreign to the body. (F) nucleotides composing polymers (G) melanin content (H) vertebrate
D