Final answer:
The most effective sentence is option B, as it is concise and directly communicates the account status without unnecessary wording. Therefore, the correct option is B.
Step-by-step explanation:
The most effective sentence among the provided options is B. Your account is now up-to-date. This sentence is concise and directly states the status of the account. It avoids unnecessary phrases like "Due to the fact that" in option A, "At this point in time," in option C, and "This is to inform you that" in option D, making it a clear and straightforward communication that is easy to understand.