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.

Researchers are developing new types of crop plants with desirable characteristics such as disease resistance and drought tolerance. Crossing plants so that the next generation will express desirable traits is best described as  
 (A) selective breeding. (B) natural selection. (C) genetic engineering. (D) gene sequencing.
A

A scanning electron microscope is best suited for observing  
 (A) diffraction of light. (B) tectonic features on planets. (C) the surfaces of small objects. (D) topographical features on the ocean floor.
C

Which of the following best describes an atom?      
 (A) protons and electrons grouped together in a random pattern (B) protons and electrons grouped together in an alternating pattern (C) a core of protons and neutrons surrounded by electrons (D) a core of electrons and neutrons surrounded by protons

C