The correct answers are Inasmuch as, That being said, and Accordingly.

Inasmuch as: A formal marker meaning "considering that" or "since." It correctly introduces the reason for his limited skills. Notwithstanding is a preposition requiring a noun (e.g., "notwithstanding his species"), and albeit is rarely used to introduce a full independent clause in this manner.

That being said: Introduces a contrasting point (his terrible spreadsheet skills versus his fantastic morale-boosting abilities). Consequently would hilariously—but incorrectly—imply that his morale-boosting is caused by his bad spreadsheet skills.

Accordingly: Means "therefore" or "as a logical result" of the productivity increase. Conversely would introduce a contrasting idea, which makes no sense for a promotion based on excellent performance.