Which of the following TOA weapons is NOT equipped with a safety selector?

The M2HB .50 caliber machine gun is not equipped with a safety selector, which differentiates it from the other weapons listed. Instead, the M2HB features a mechanical safety mechanism involving a lever that must be engaged to prevent accidental discharge, but it does not have a safety selector that can change the firing mode between safe, semi, and automatic like the other weapons.

In contrast, the M240 machine gun, the M249 SAW, and the Mk19 Grenade Machine Gun each have a safety selector that allows the operator to select between different modes of fire or to engage a safety position. This design provides operators with more control over the weapon's operation, particularly in combat scenarios where the ability to quickly switch firing modes is crucial. The absence of a safety selector on the M2HB underscores the difference in design philosophy and operational use compared to these other weapons.