Using a standing desk promotes more muscle activity and, as a result, better circulation. ________, employees with standing desks tend to be more productive than employees who sit at traditional desks.

For example
Furthermore
First
Therefore

Moreover

Will any of the provided answers work fine?

Yes, all of the provided answers can work well to connect the two statements in the sentence.

If you were to make an educated guess, would For example, Furthermore, First, or Therefore fit best

In this case, "Therefore" would fit best to show a logical conclusion based on the information provided in the first part of the sentence. It indicates that the increased muscle activity and better circulation resulting from using a standing desk lead to increased productivity among employees.