Answer:
I will give a hypothesis. Just like a tree, when you cut a tree by its trunk, you will the rings. The rings around it represents the tree's age. So when you cut rock, the pores in the rock determine whether it is an old rock or a fossil rock.
Explanation:
The reason is, if it is limestone and it is an old rock, the pores will be slightly big and if the limestone is a fossil rock, then the pores will be bigger due to leaching or denaturing of the minerals in the rock through the ages.
When focusing on a slide, ALWAYS start with either the 4X or 10X objective. Once you have the object in focus, then switch to the next higher power objective.
4.6 billion years ago
The study pushes back the clock on the origin of Earth's water by hundreds of millions of years, to around 4.6 billion years ago, when all the worlds of the inner solar system were still forming. Scientists had suspected that our planet formed dry, with high-energy impacts creating a molten surface on the infant Earth.
i hope this helped, have a nice day! (o:
B is the answer. But the changes would take over time