I would agree with Wayne's suggestion here. This task looks like a language use task from a Cambridge exam. If that is the case, what they want you to do in tasks like this is change the grammar of the sentence without changing the meaning. So if you say "The boss is said to be leaving the company soon" you change the grammar but not the meaning. To explain it a bit more, ''The boss is said" is the same as "They say the boss" (both show "the boss" as the object of the action/he's passive/) and "will be leaving the company soon" is the same as "to be leaving the company soon" (both have future meaning). Hope this helps ))

I agree that the best answer is "The boss is said to be leaving the company soon." This is the appropriate grammar for upper-level English. Unfortunately "The boss said..." is not right, because the first sentence doesn't indicate that. "Other people" say that, not the boss. Stay close to the grammar on a test question like this.

Your answer b) is good. Also: The boss is said to be leaving the company soon.

Both sentences are grammatically correct, but this should be better: The boss said he will be leaving the company soon.