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.
The speed of light is 299,792,458 meters per second in vacuum.
It's somewhat slower in any material substance, and different in
each substance.
(That's 186,282.4 miles per second.)
The log of the hydronium ion concentration
Answer:
Bohrium (Niels Bohr)
Curium (Marie and Pierre Curie)
Einsteinium (Albert Einstein