Options are:
1). roof weathering
2). Plant growth is reduced
3). brick weathering
4). Physical weathering
5). remains of prehistoric life
6). at or near the margins
7). home weathering
8). major threat to health
Given those answer options, answer the question: You are presented with the quiz "What is when rocks are broken down?" But you don't know the answer, so you turn to your teacher to ask for hints. He says that "mechanical weathering is when rocks are broken down by mechanical means" and "pysical weathering is the mechanical breakdown of rocks". So, what's the best answer to the question?
A:
4).