How long does it usually take for a rock to be transformed from one rock type into another?
a.
a few days
b.
from 300 to 400 years
c.
about one thousand years
d.
thousands to millions of years

D thousands to millions of years because The erosion of rocks takes really long.

For example: The waves attack the headland and then over a course of millions of years it transforms into a cave, then an arch, next a stack and lastly a stump.

Apart from erosion rock transformation can be affected by weathering.

I hope I've helped, I'm studying it in Geography in school at the moment so I'm pretty sure it's correct! ☺

the correct answer is:

this is an example of the writer telling through description rather than showing through dialogue.

sometimes writers like to explain explicitely what's happening instead of adding dialogues of the situations., which is the case in this passage,

b is the answer for this question.