The correct answer is: A. Can hold more data.
A dual-layer DVD is a DVD that can store twice as much data as a single-layer DVD. This is because it has two layers of data, one on top of the other. Dual-layer DVDs are often used to store high-definition video or large amounts of data.
Option B is incorrect because a dual-layer DVD does not contain a backup of the data stored on it. If the data on a dual-layer DVD is lost or damaged, there is no way to recover it.
Option C is incorrect because a dual-layer DVD does not use a second layer to offer a speed increase. The speed of a DVD is determined by its rotational speed, not by the number of layers it has.
Option D is incorrect because a dual-layer DVD does not create alternative sound tracks. A dual-layer DVD can store multiple audio tracks, but these tracks are all played at the same time.