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.

[EX Q]: Which set contains kingdoms that contain only heterotrophs?   
 (A) Protists, Fungi (B) Bacteria, Animals (C) Plants, Fungi (D) Animals, Fungi
[EX A]: D

[EX Q]: 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
[EX A]: A

[EX Q]: Which of these will best separate iron filings from sand?  
 (A) water (B) a magnifying glass (C) a magnet (D) rubbing alcohol
[EX A]:
C