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.

Q: A scientist is searching for areas where new solar systems might form. What feature is the scientist looking for?  
 (A) a star similar to our Sun (B) a cloud of dust and gas (C) an oxygen-rich atmosphere (D) a gravitational acceleration of 9.8 m/sec2

A: B
****
Q: 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

A: B
****
Q: Which difference between land and water contributes most directly to global climate change resulting from tectonic movement?  
 (A) mean material densities (B) magnetic material content (C) heat absorption and retention properties (D) rate of radioactivity-related heat release

A:
C
****