<u>Answer:</u>
<em>The exposure of sea bed or undersea surface is called sea-level regression.</em>
<u>Explanation:</u>
Sea-level regression occurs when sea level drops down due to several climatic changes. This triggers extinction of several species. There had been several mass extinctions in the past due to <em>sea-level regression.
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<em>Chances of survival of shallow</em> water species become feeble when the sea level falls. In the case of mass extinctions regression can be seen as a symptom and not a cause.
Marine transgression is the opposite <em>phenomena of regression</em> where sea level rises and covers the land which was previously above the sea level.
Answer: (A) Natural selection tend to reduce genetic variation as there was a smaller distribution of beak depths, but it tends to select for the most fit phenotypes, as there was an increase in average beak depth after the drought.
Explanation: The picture below shows proof if needed. On USATP
Answer:
A covalent bond.
Explanation:
A covalent bond, also called a molecular bond, is a chemical bond that involves the sharing of electron pairs between atoms.
The answer to this question is A) Biomass!
