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.

Where do good bacteria grow to help keep people healthy?  
 (A) in the brain (B) in the blood (C) on the skin (D) on the bones
C

A student has just completed a laboratory activity. What is the last action that the student should perform before leaving the lab area?  
 (A) wash hands (B) turn off all equipment (C) put away all glassware (D) wash instruments and table tops
A

A scientist studies how weathering and erosion can change the shape of a mountain. The scientist needs to collect information over what period of time to gather the most accurate information?  
 (A) days (B) weeks (C) months (D) years

D