Problem:OPTIONS:
- density
- kinetic
- volume
- simple
- forces
- grams
- Joules
- viscosity

You are presented with the quiz "what is a balance used for measuring in an object?" But you don't know the answer, so you turn to your teacher to ask for hints. He says that "abalance is used for measuring mass of an object" and "mass The base unit of mass is the gram". So, what's the best answer to the question?
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A: grams

Problem:OPTIONS:
- Loose
- Wind
- With sand
- fibers
- heat
- Dry
- store
- Tight

You are presented with the quiz "How should the soil be packed for the plants to grow healthy?" But you don't know the answer, so you turn to your teacher to ask for hints. He says that "the looseness of soil has a positive impact on a plant 's roots' growth in that soil" and "root growth and development are extremely important to plant growth". So, what's the best answer to the question?
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A: Loose

Problem:OPTIONS:
- rivers
- dirt
- liquid
- light
- rainy
- sun
- rain
- floods

You are presented with the quiz "What may streams start as?" But you don't know the answer, so you turn to your teacher to ask for hints. He says that "streams may start with runoff or water seeping out of a spring" and "rain is assumed to occur as direct runoff". So, what's the best answer to the question?
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A: rain

Problem:OPTIONS:
- garbage
- Generating heat
- Space travel
- running and lifting
- Time and energy
- exercise
- money
- Riding a bike

You are presented with the quiz "What is one way animals learn to behave?" But you don't know the answer, so you turn to your teacher to ask for hints. He says that "playing is one way mammals and other animals learn how to behave" and "involvement in play takes time and energy". So, what's the best answer to the question?
****
A:
Time and energy