What is an adjustment layer used for in Premiere Pro?

An adjustment layer in Premiere Pro is specifically designed to apply effects to multiple clips at once. When you create an adjustment layer and place it above your video clips on the timeline, any effects applied to that adjustment layer will affect all underlying clips. This allows for cohesive color grading, transitioning, or other effects across multiple elements in your project without the need to apply the same effect individually to each clip. This is especially useful for maintaining a consistent look throughout your video or for effects that you want to be uniform across several clips.

The other options do not accurately reflect the primary function of an adjustment layer. Applying effects to a single clip involves directly manipulating that clip rather than using a shared layer. Adjusting audio levels across multiple tracks typically requires using audio mixing techniques or buses instead of an adjustment layer. Creating a new video sequence is a separate function unrelated to adjustment layers, as sequences are the foundational building blocks for organizing and editing multiple clips.