Problem:OPTIONS:
- It becomes dormant
- negative charge
- kinetic energy
- energy barrier
- heat energy
- Electrical energy
- hydrogen and oxygen
- activation energy

You are presented with the quiz "what can an ion have if it loses an electron?" But you don't know the answer, so you turn to your teacher to ask for hints. He says that "if a neutral atom loses an electron then an atom with a negative charge will be formed" and "ions are neutral atoms". So, what's the best answer to the question?
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A: negative charge

Problem:OPTIONS:
- HIV
- lack
- DDT
- p53
- antibiotics
- h2o
- memory cells
- HPV

You are presented with the quiz "what causes the immune system to not work properly?" But you don't know the answer, so you turn to your teacher to ask for hints. He says that "immunodeficiency occurs when the immune system is not working properly" and "hIV, the human immunodeficiency virus, is a retrovirus". So, what's the best answer to the question?
****
A: HIV

Problem:OPTIONS:
- an object
- eukaryote
- bacteria
- layers of fat
- They may not survive.
- chlorofluorocarbons
- Tobacco mosiac
- prokaryote

You are presented with the quiz "What is not a cell?" But you don't know the answer, so you turn to your teacher to ask for hints. He says that "viruses are not cells at all, so they are neither prokaryotes nor eukaryotes" and "viruses include the Tobacco Mosaic Virus". So, what's the best answer to the question?
****
A: Tobacco mosiac

Problem:OPTIONS:
- storms
- oil
- cars
- coal
- air
- wind
- carbon
- water

You are presented with the quiz "what causes global warming?" But you don't know the answer, so you turn to your teacher to ask for hints. He says that "gases released during the use of fossil fuels causes global warming" and "fossil fuels are coal, oil, and natural gas". So, what's the best answer to the question?
****
A:
coal