Select the most appropriate degree of comparison to fill in the blank.
Work in this office is done in the _________ way.

Correct option is A

Explanation:
This sentence refers to the lowest level of efficiency, which requires the superlative degree of the adjective efficient.
The correct superlative form of efficient is least efficient, used when referring to the lowest point in comparison.
Rule: Degrees of Comparison
Positive Degree: Describes a single item — efficient.
Comparative Degree: Compares two items — more efficient.
Superlative Degree: Compares more than two — most efficient or least efficient (for negative qualities).
Example:
Among all the departments, this one is the least efficient.
He is more efficient than his colleague.