It takes 2 years of graduate study in a subfeild, practicum experience, and a thesis.
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Answer:
earth strong gravity
Explanation:
The only planet that have water bodies is earth. We know that water is one of the important factors for all living organism. Liquid water exists on the earth's surface is due to the atmospheric pressure. The reason behind this is not completely mentioned.
There are so many hypothesis about it. Out of given options the correct option is earth's strong gravity.
Hence, the correct option is (b) " earth strong gravity ".
I believe the answer should be D
