Which method allows for visualizing trajectories using a laser?

Using photographic fog to see the laser is the correct method for visualizing trajectories. When a laser is used in crime scene investigations, the beam may not be visible to the naked eye unless it illuminates a particle in the air. Photographic fog or similar mediums can create a visible effect, allowing investigators to see the trajectory of the laser beam as it travels through the space. This technique enhances the ability to demonstrate the path of bullets or other projectiles by visualizing the laser's straight line, which is essential when reconstructing events at a crime scene.

The other methods mentioned do not effectively visualize the trajectory of a laser beam in the same way. Marking terminal points with chalk only establishes physical points but does not help in visualizing the path of a trajectory. Measuring angles with a protractor pertains more to calculating angles rather than visualizing the laser path itself. Employing 3D modeling software can assist in simulation and analysis but does not involve immediate visualization of the laser in the physical space during the initial investigation.