Which of the following factors can impact bullet trajectory?

The correct choice highlights the significant impact that both humidity and wind direction can have on bullet trajectory.

Humidity affects air density; as humidity increases, the air becomes less dense since water vapor is lighter than nitrogen and oxygen. This change in air density can change how much drag the bullet experiences throughout its flight. Bullets may travel farther in humid conditions compared to dry conditions, necessitating adjustments in aiming to maintain accuracy.

Wind direction also plays a crucial role in bullet trajectory. When firing at a target, wind can push the bullet off its intended path, necessitating an adjustment for the wind's direction and speed. An understanding of how wind interacts with the bullet during its flight is essential for making precise shots, especially over longer distances.

The combination of these two factors—humidity affecting the air density and wind influencing lateral movement—profoundly affects how exactly a bullet travels towards its target. Thus, recognizing their influences is critical for accurate shooting in various environmental conditions.