The anti-exposure coveralls have an orally inflated device for what purpose?

The anti-exposure coveralls include an orally inflated device primarily to enhance buoyancy. This feature is crucial because it helps to increase the wearer's flotation capability in the water, which is vital for survival in cold water scenarios. When the oral inflation device is activated, it adds buoyancy, helping to keep the head above water, which is essential for both safety and maintaining a proper flotation position. This additional buoyancy can significantly reduce the risk of drowning and allow for easier recovery by rescue personnel.

The other options, while related to the use of anti-exposure coveralls, do not accurately describe the primary function of the orally inflated device. The focus on flotation angle and overall buoyancy is what truly underscores its importance.