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 statement best describes the development of a human embryo?
(A) A single cell becomes many cells. (B) Each cell has a different function. (C) Many cells combine to form one cell. (D) All the cells have the same function.
A

Why should plants be included in investigations about the water cycle?
(A) Plants speed up the water cycle by removing carbon from the air. (B) Plants start the water cycle when they make water in photosynthesis. (C) Plants are part of the water cycle through the process of transpiration. (D) Plants stop the water cycle because they absorb it and stop the flow to streams.
C

Roger visited his grandfather who lives on a farm. While he was there, he helped his grandfather move hay out of the barn. As Roger worked in the barn he began sneezing. Which system of the body most likely caused Roger to sneeze?
(A) circulatory (B) excretory (C) digestive (D) immune
D