Problem:OPTIONS:
- fossil fuels
- humans disturb it
- Organic compounds
- harmful substances
- chlorofluorocarbons
- carbon dioxide
- sulfur dioxide
- Greenhouse gases

You are presented with the quiz "The environment is polluted when what is emitted?" But you don't know the answer, so you turn to your teacher to ask for hints. He says that "the emission of sulfur dioxide causes acid rain" and "aCID RAIN Acid rain is polluted and harmful to the environment". So, what's the best answer to the question?
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A: sulfur dioxide

Problem:OPTIONS:
- graptolites
- more abundant
- multicellular
- fertile
- homogenous
- Allergies
- Conifers
- aerobic capacity

You are presented with the quiz "What type of organism are fungi?" But you don't know the answer, so you turn to your teacher to ask for hints. He says that "fungi spores can develop into new haploid individuals without being fertilized" and "fungi are filamentous, multicellular, haploid organisms". So, what's the best answer to the question?
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A: multicellular

Problem:OPTIONS:
- leave an environment
- population movement
- reproduce
- growl
- Damages them
- thrive
- cause their death
- to move people

You are presented with the quiz "Floods can cause animals to do what?" But you don't know the answer, so you turn to your teacher to ask for hints. He says that "natural disasters can cause animals to leave an environment" and "floods are the most common natural disaster". So, what's the best answer to the question?
****
A: leave an environment

Problem:OPTIONS:
- oil
- sugar
- coal
- Cars
- H2O
- CO 2
- He
- O2

You are presented with the quiz "What has increased in the air dramatically over the last decade?" But you don't know the answer, so you turn to your teacher to ask for hints. He says that "carbon dioxide concentrations in the air have increased over the last decade dramatically" and "cO 2 is carbon dioxide". So, what's the best answer to the question?
****
A:
CO 2