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.

Ex Input:
During a walk in the woods, Mandy finds a plant structure that had fallen onto the trail. Mandy can tell the object contained seeds, and thinks it came from a flowering plant instead of a conifer. How can she determine if the object came from a flowering plant?  
 (A) by looking for seed coats on the seeds (B) by looking for wing-like structures on the seeds (C) by looking for fruit tissue around the seeds (D) by looking for young sporophytes inside the seeds

Ex Output:
C


Ex Input:
Some types of bacteria can only live where oxygen is not present. These bacteria were well adapted to life on Earth over 2 billion years ago. Which of the following changes caused many of these bacteria to become extinct?  
 (A) the slow movement of tectonic plates (B) the varying temperatures of each season (C) an increase in volcanic activity under the oceans (D) an increase in the number of photosynthetic organisms

Ex Output:
D


Ex Input:
Which of the following is the main role of flowers found on most flowering plants?  
 (A) to take in air (B) to produce seeds (C) to absorb nutrients (D) to protect the stem

Ex Output:

B