You are given a science question (hard-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.

Input: Consider Input: Which of the following is a similarity 20 between x-ray waves and sound waves?  
 (A) Both transfer energy. (B) Both require a vacuum. (C) Both have the same speed. (D) Both have the same frequency.

Output: A


Input: Consider Input: Which of these is never found in prokaryotic cells?  
 (A) cell membrane (B) ribosome (C) cell wall (D) nucleus

Output: D


Input: Consider Input: El Cajon Pass in California is becoming higher than the land around it at a rate of nearly one centimeter each year. Which statement is true about the area?  
 (A) Erosion is slower than uplift at El Cajon Pass. (B) Plates are separating at El Cajon Pass. (C) Mountain building is slower than erosion at El Cajon Pass. (D) Erosion and uplift are balanced at El Cajon Pass.


Output: A