The answer is C.
Using social media is free.
This is irony.
It is irony because war is anything but kind. Alliteration would be if both words started with the same letter. Style is not a device, and a simile is when you compare something to something.
The linking verb, otherwise known as the copula verb, is was. Assassinated is the main verb, while was is the linking one.
D. sentences
Mom washed the dishes and I had to dry them are both independent clauses. But is a conjunction that connects both.
The correct answer to your question is the 1st option or option A. (emptiness)