1. The problem asks to identify the term that describes the segment FD in triangle EFC. 2. The key information is that the angle at point D between segments FD and DE is a right angle (90 degrees). 3. Definitions: - Altitude: A segment from a vertex perpendicular to the opposite side. - Angle bisector: A segment that divides an angle into two equal angles. - Perpendicular bisector: A segment that is perpendicular to a side and bisects it. - Median: A segment from a vertex to the midpoint of the opposite side. 4. Since FD is perpendicular to DE at D, and D lies on side EC, FD is an altitude from vertex F to side EC. 5. Therefore, FD is an altitude of triangle EFC. Final answer: FD is an altitude.