Answer:
C. The samples contain the same substances in a fixed proportion.
As the rock breaks into smaller pieces, the surface area of the pieces increases<span> Figure below. With more surfaces exposed, there are more surfaces on which </span>chemical weathering<span> can occur. Mechanical </span>weathering<span> may </span>increase the rate of chemical weathering<span>.
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1. Calling for attention could mean asking for a mate, or simply marking territory.
2. The rattlesnake's rattle serves as a warning to all its prey and predators.
3. A sweet scent for a plant attracts insects to pollinate their flowers.
4. Some may have a unique way of calling out, or weird movements. Take tropical birds for example.
5. I think it's because that the females are attracted to a certain call or movement.
6. communication is talking to each other.
7. Stimuli can induce the hypothalamus in an organism's brain to react accordingly.
8. Animals need a voice, or a call, or a maovement, or anything to get their point across.
That was a lot of typing, but i'm done. :)