Answer:
In my opinion it could be physical or chemical weathering!
But in case of no chemical actions/means, then the answer is physical weathering!
Step-by-step explanation:
When a plant in the ground sprouts its roots into rock, there are possibilities that occur in this process!
a. The plant can give/let off a chemical substance, such like acid, and other types of chemical substances that may break down the rock, causing it to weaken and crack and/or break apart. This is the process known as chemical weathering.
b. Physical weathering: where the plant will work its way into areas where there may be cracks, also called cervices, that you may see on the road, sidewalk, etc. After the plant settles in, the roots will start to spread throughout the ground, creating pressure, and pushing outwards onto the cracks, which make the rock(s) break apart even more!