Which of the following is an example of mechanical weathering
a. gravity
b. oxidation
c. acid formation
d. lava intrusion

The answer is A-Gravity. Why? This is because B and C are examples of chemical weathering and not mechanical. Although choice D may seem viable lava intrusion is not a direct cause of mechanical weathering although lava pushing upward may help in aiding mechanical weathering it would not be considered a big enough cause, thus gravity is the correct answer.

Variables,control,conclusion and finally scientific theory