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.

Cells come in two basic types, prokaryotic and eukaryotic. Which cell structure is found in both prokaryotic and eukaryotic cells?  
 (A) vacuole (B) nucleoid (C) mitochondrion (D) cytoplasm
D

Some plant species are more tolerant of acidic soil than others. The tolerant species are favored in areas affected by which consequence of human activity?  
 (A) mixing of pollutants with rain (B) erosion of topsoil by clearcutting (C) runoff of fertilizer used in farming (D) thinning of the atmospheric ozone layer
A

The human brain is an organ that is made up of many tissues. This information can be used to determine that the brain is  
 (A) unicellular. (B) multicellular. (C) part of a bacterial colony. (D) able to function independently.

B