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.
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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.

Answer: A

Question: A condition in bees called "colony collapse disorder" occurs when worker bees leave the hive to collect nectar and never return. How would a decline in the bee population most likely affect a farm ecosystem?
(A) There would be a decrease in soil thickness. (B) There would be a decline in fruit production. (C) There would be an increase in plant diseases. (D) There would be an increase in insect pest populations.

Answer: B

Question: Which of the following is designed to convert energy into mechanical work?
(A) Electric fan (B) Kerosene heater (C) Flashlight (D) Baking oven

Answer:
A