What are the different display options for?

Option

The options contain 4 settings, the first three control the display of carriers in the scene and the last one is used to display the composition lines.

The carriers in the scene are: light carrier, particle carrier, and path carrier. The carriers are shown by default, click the icon, and a slash appears to indicate that the carrier of that type is hidden in the scene.

Shortcut L can hide all three carriers at the same time with one click.

The composition line currently divides the frame into three equal parts to assist in the composition of the image.