Fluorine in compounds is always assigned an oxidation number of -1
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 answer to the question
Rubidium would exhibit the greatest shielding [ effect. ]
