According to 46 CFR §28.510, what is the definition of 'downflooding angle'?

1. A. The angle at which the vessel's righting arm reaches its maximum value
2. B. The angle at which the vessel's keel first contacts the seabed
3. ✓ The static angle from the intersection of the vessel's centerline and the waterline in calm water to the first opening that cannot be closed weathertight and through which downflooding can occurCorrect
4. D. The angle of heel at which the area under the righting arm curve equals zero