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]: Carolina uses a microscope to view a soil sample taken from her backyard. Which part of the soil would she ONLY be able to see with a microscope?  
 (A) bacteria (B) grass (C) rainwater (D) rocks
[A]: A


[Q]: Which land feature is formed from erosion by waves?   
 (A) a sandbar (B) a sea cliff (C) a barrier reef (D) a barrier island
[A]: B


[Q]: Biologists moved a predator from sea level to a higher altitude, where they noticed that the predator became tired more quickly. If this predator had to live at a higher altitude, which adaptation would be necessary for it to survive?  
 (A) increased digestion rate (B) growth of additional teeth (C) reduction of respiration rate (D) production of more red blood cells
[A]:
D