
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! ☺