What is the first step to evenly distribute images vertically in PowerPoint?

To evenly distribute images vertically in PowerPoint, the initial step involves using the Align button on the Picture Tools Format tab. When you select multiple images and access the Picture Tools Format tab, the Align feature provides various alignment and distribution options that help organize your images neatly. Choosing to align the images first allows you to set a baseline for all selected objects. After aligning, you can then apply the distribute option to ensure that the spacing between each image is equal, achieving an organized and visually appealing layout.

This step is crucial because it directly relates to how PowerPoint handles alignment and distribution together, streamlining the process of arranging multiple images in a structured manner. The other options involve different functionalities that may not effectively contribute to the goal of vertically distributing the images from the outset.