TASK DEFINITION: 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.
PROBLEM: Fertilizers can enable farmers to grow the same crop in a field for several years in a row. Farmers who use less fertilizer often rotate their crops by planting the crop one year and legumes, such as beans and clover, the following year. Fertilizer use and crop rotation with legumes both increase the availability of which of the following nutrients in soil?  
 (A) calcium (B) nitrogen (C) oxygen (D) protein

SOLUTION: B

PROBLEM: Which of these shows the correct order for the central dogma of molecular biology?  
 (A) DNA to protein to RNA (B) RNA to DNA to protein (C) protein to DNA to RNA (D) DNA to RNA to protein

SOLUTION: D

PROBLEM: Some animals have advantages and disadvantages because they are different. Which of the following has a disadvantage compared to other animals in its population?  
 (A) a polar bear that has dark-colored fur (B) a deer with long legs (C) a rabbit that can run fast (D) a hummingbird with a long beak

SOLUTION:
A