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.

Which unit of measurement describes an object's length?  
 (A) meter (B) kilogram (C) liter (D) degree
A

The pull of gravity from Earth has the greatest effect on  
 (A) comets. (B) the Sun. (C) asteroids. (D) the Moon.
D

Michelle is interested in improving the quality of the soil in her yard. She wants more water and air to penetrate the soil. What should she add to the soil to help her achieve this goal?  
 (A) bacteria (B) fertilizers (C) pesticides (D) earthworms

D