You are given an elementary science question along with a few answer options. List all the words from the question that are essential and sufficient for choosing the correct answer option. Keep in mind that essential words are necessary to understand the meaning of the given question. However, non-essential words provide little information needed to select the correct answer. You can think about it like this: If the question was in another language, knowing the meaning of which words were necessary and enough for you to understand the question and answer it?. If your answer consists of multiple spans of words from the question, separate those using a comma (", "). Do not generate any word that is not present in the question. Make sure that your response is contained in the given question and the words are in the same order as the question.
 Grammatical correctness is not important.

Question: A simple electromagnet can be made by wrapping metal wire around a nail, and attaching the ends of the wire to an electrical source. When the electrical source is turned on, the nail will (A) repel substances that normally respond to magnets. (B) reverse the flow of the electric current. (C) complete the circuit and cause the light bulb to light. (D) attract substances that respond to magnets.?
electromagnet, wrapping, wire, electrical, source., nail

Question: What part of DNA contains hundreds of pieces of information? (A) tissues (B) chromosomes (C) muscles (D) blood cells?
part, DNA, hundreds, pieces, information?

Question: All the ponds in an area dried up during a drought. The population of which of the following animals that live in the area is most affected by the drought? (A) deer (B) frog (C) hawk (D) squirrel?

ponds, dried, population, animals, affected, drought?