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.

Example Input: As Archie walks to the park, he wonders which route would be faster. He decides to walk to the park using different routes and times how long it takes. Which should he do to make his comparison fair?
(A) walk to different parts of the park each day (B) walk with a different friend each day (C) walk at the same speed each day (D) walk at the same time of the day
Example Output: C

Example Input: The cactus moth was deliberately introduced to Australia in 1926 as a biological control for an invasive prickly pear cactus. By the early 1990s the moth had also migrated to the Florida Keys from South America and the moth soon eliminated most of the semaphore cacti in the region. Since then, the moth has adapted to eat other plants in the Keys and has continued to grow in number. Which procedure would most likely reduce the population of the cactus moth?
(A) Release sterile moths to limit reproduction. (B) Use widespread spraying of insecticides. (C) Introduce a predator of the cacti. (D) Stop importation of all types of plants.
Example Output: A

Example Input: Laura adds 50 mL of boiling water to 100 mL of ice water. If the 150 mL of water is then put into a freezer, at what temperature will the water freeze?
(A) 0C (B) 15C (C) 37C (D) 50C
Example Output:
A