Answer: A cold front occurs when cold, denser air replaces the rising, less dense air mass. The reason this front brings in the rain is that as the rising warm air cools (as it rises to the cooler upper atmosphere) the moisture in it condenses into clouds that precipitate down as rain or snow.
A if it is one answer and if it’s multiple choice A and D
Answer: I think the answer is d
Explanation: sry if wrong
Refraction: It is the phenomena of bending of light when it changes it medium. This can rarer to denser or denser to rarer. Refraction and Diffraction are just bending of light. Whereas, Reflection is getting back the light you've thrown from a source of light.