The correct option is B He was asked to resign today. He isn't in a very good mood.
A compound sentence is made up of two independent clauses, which are
complete sentences on their own. Illative compound sentences contain
clauses where one is inferred or deduced from another; for example, "There's someone in the hall for the light is on", where "for" is an
Illative conjunction. From the given options, B contains suitable clauses that can be combined with 'therefore'. "He isn't in a very good mood." is concluded from "He was asked to resign today." hence option B is correct. In A, the clauses do not express any relation, they can only be added to one another, hence A is incorrect. In option C, the sentences contrast each other in meaning ("She has been sick, yet she is lively and happy"); hence C is incorrect. Option D shows a choice between two alternatives ("You can either come here and work or you can work from home"); hence D is also incorrect.