Ser is used in a simple way, to talk about WHAT something is (permanent state). To describe characteristics that are an essential part of the thing we're talking about. Estar is used to talk about HOW something is, so we use it for conditions, locations, emotions, and actions (temporary states).
9 says "On December 5th today in Boston it is cold and snowing." so it is b
The answers are, A,D,B,C. Hope this helps !
Cómo estás is the best answer since the rest have been answered and said in the dialogue
