Detailed Instructions: You are given a science question (easy-level) and four answer options (associated with "A", "B", "C", "D"). Your task is to find the correct answer based on scientific facts, knowledge, and reasoning. Do not generate anything else apart from one of the following characters: 'A', 'B, 'C', 'D'. There is only one correct answer for each question.
Problem:The cells of organisms found in the phylum Porifera (sponges) are not organized into tissues. What structures are absent in organisms belonging to the phylum Porifera?
(A) organelles (B) cells (C) genes (D) organs
Solution:
D