If you accidentally double click on a layer, the layer panel opens and covers up which panel?

When you double-click on a layer in Adobe After Effects, the layer panel opens, providing detailed information about the selected layer. The composition panel is the key interface where you can view and manipulate your project visually, and since the layer panel opens as a new window, it typically appears over the composition panel. This design choice helps users focus on editing specific layer properties without losing sight of the overall composition they're working on.

The other panels, such as the Effects Control panel, Audio panel, and Timeline, do not behave in the same way as the composition panel in relation to the layer panel. The Timeline panel, while part of the overall interface, remains visible and does not get covered up in the same manner when you double-click a layer. Therefore, the most accurate answer is that the layer panel covers the composition panel, allowing users to work on their layers with a better understanding of how adjustments would affect the entire composition.