Answer:
A. Circumcenter
Explanation:
this is the point that has the same distance from all 3 vertexes.
being on the median line of DE, every point of that line has the same distance to D and E.
being also on the median line of FE means it has the same distance from F and E as every other point on that line.
and the same for DF.
H as the crossing point of all 3 median lines is the only point that has the same distance to D, E and F.
so, H is the center of a circle that goes through all 3 points.