Final answer:
Clicking the double arrows above a single-column tools panel switches it to a multi-column view, increasing visibility and spreading out available tools.
Step-by-step explanation:
When you click the double arrows just above the tools panel when it is in a single-column view, it switches the Tools Panel to a multi-column view. This is option c) It switches to a multi-column view. With a multi-column view, you gain better visibility of all the tools that are available in a more widespread manner. It's basically providing a different format of visualizing the tool panel, giving you more screen real estate if you have a larger monitor and don't need to economize screen space.
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