The speed of seismic waves varies as they travel through Earth because
A. Temperature varies within the Earth
B. Density of rocks varies within the Earth
C. The composition of rocks varies within the Earth
D. All of the above
Help pleasee

Here's link to the

tinyurl.com/wpazsebu

I think its C but you can choose B&C

Explanation:

A (and D) is not the answer because natural disaster dosent matter with temperatures.

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if the type of the food available changes, then the frequency of beak types will change, because birds with beaks more suited to the available food will be more successful over time.