What does the Direct Selection Tool do?

When the brush tool is selected, how can you change its opacity to 75% by using the keyboard instead of the slider?

Which one is NOT a category under Preferences?

Under which menu is the Displace option located?

Which one is the use for alpha channels?

Where can you find the option to reverse the layer order?

Which is NOT a texture option on the Underpainting filter?

Shortcut for Auto Tone?

Which one is NOT included in the purge menu?

Which type of files can be used as a displacement map on the displace filter?

Which file format supports 16-bit color, 8-bit color, indexed color, grayscale, and alpha channels, but not CMYK?