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.
--------
Question: When a tree suffers from a decreased ability to transport materials within the phloem, what is directly impacted?
(A) volume of water in the xylem (B) flow of necessary nutrients (C) response to environmental factors (D) rate of photosynthesis in leaves

Answer: B

Question: Historically, how has the compass been used?
(A) for navigation (B) to predict weather (C) to measure temperature (D) for mineral identification

Answer: A

Question: A student wants to find the most accurate account of a scientific discovery that took place within the past three months. In which of these sources should the student look?
(A) newspapers (B) magazines (C) science textbooks (D) science journals

Answer:
D