the day are becoming shorter and shorter ___ it is now December A) when B) for C) after D) until

the day are becoming shorter and shorter ___ it is now December A) when B) for C) after D) until

B for
Because, leading reason

What it is like when the days are so short?

If this is a complete sentence, it should be an exclamatory sentence, because the main sentence is in declarative order
What is it like
Whether it is an interrogative sentence or an exclamatory sentence depends on whether there is a question mark behind it

the days are very short______ December
Fill in the preposition?

In and during are OK, but I think the latter is more authentic