Choose the correct preposition to fill in the blank in the sentence given below.

The newly appointed manager was highly regarded ________ the team members shortly after taking charge.

The correct answer is among.

Explanation:
The given sentence requires a suitable preposition to complete the thought logically and grammatically:
"The newly appointed manager was highly regarded ________ the team members shortly after taking charge."

Let's analyze the options:
1. among: The preposition "among" is used when referring to inclusion, placement, or shared opinion within a group of three or more individuals or items. Here, "highly regarded among the team members" correctly expresses that the manager is held in high esteem by the group as a whole.
2. with: Indicates accompaniment, possession, or tool/instrument, which does not convey being held in high regard within a collective group.
3. upon: Means "on" or "onto", which is grammatically incorrect in this context.
4. across: Means from one side to another or throughout a geographical area, which does not fit the context of personal esteem or opinion.

Therefore, among is the correct preposition to complete the sentence.