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: Water in the solid phase has a crystal structure which keeps molecules farther apart than water at certain temperatures in the liquid phase. This relationship explains which property?
(A) the presence of more impurities in ice than in liquid water (B) the ability of ice to float on liquid water (C) the release of heat when liquid water turns into ice (D) the cooling of liquid water as it flows over ice

Output: B

Input: Consider 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.

Output: A

Input: Consider Input: When prehistoric animals died and their soft parts decayed, which product was formed?
(A) oil (B) sand (C) coal (D) shale
Output: A