Answer:
A) the pressure of Earth's crust upon Earth's mantle
The process which planetesimals combine with other planetesimals is called Accretion.
There are other names which refer to as accretion. For example, Accretion geology is termed as the increase in the size of a tectonic plate by addition of materials which convergent boundary.
Accretion atmosphere is termed as the process by which water vapor which is in clouds forms water droplets around nucleation sites.
Accretion astrophysics is termed as the formation of planets and other bodies through a collection of material through gravity.
In broad terms, finches. In specific terms, he observed how over time, the beak sizes and shapes of said finches changed to adapt to the food sources available.
I hope I was able to help. Best of luck.
