Final Answer:
The intersection of plane ABF and plane EGH is a line.
Step-by-step explanation:
When two planes intersect, the result is typically a line. This line is the set of points that lies on both planes simultaneously. In the context of the given planes ABF and EGH, the intersection forms a line rather than a single point, ray, or segment. This is a fundamental geometric principle related to the intersection of two planes in three-dimensional space.
The line of intersection can be visualized as the common boundary between the regions where points belong to plane ABF and plane EGH. It is the locus of points that satisfy the equations of both planes simultaneously. The intersection of planes is often a line unless the planes are parallel or coincident, in which case the intersection could be a single point or an entire plane.
In conclusion, the correct answer is that the intersection of plane ABF and plane EGH is a line. This understanding aligns with geometric principles and the typical outcomes of plane-plane intersections in three-dimensional space.