The correct answer is A. To present identical content on multiple displays. Display mirroring is used when the same screen image must appear on more than one display, such as a laptop screen and a projector in a conference room. This is useful for presentations because the audience sees the same content the presenter sees. Mirroring does not improve cloud speed, add security by itself, or share files from network-attached storage.
Exact Extract/Reference: The Tech+ Study Guide explains that when "two or more displays are used at the same time to project the same image, that is called mirroring." It also states that "all actions performed on one display" are shown on the mirrored display.