One AP will cover a square office from a central location. Which antenna type provides even 360° coverage for this placement?

An omnidirectional antenna is the correct choice because it radiates RF signals equally in all directions (360 degrees) horizontally, making it ideal for central placement in an open area like a square office to provide uniform coverage. Directional antennas focus their signal in a specific direction, which would leave large areas of the office without coverage. Polarized refers to the orientation of the electromagnetic waves, not the coverage pattern. A Yagi antenna is a type of highly directional antenna, unsuitable for this scenario.