Which center of triangle?

The point of intersection of all perpendicular bisectors of a triangle is the $\color{#3D99F6}{\boxed{\text{circumcenter}}}$ of the triangle.

It is not the incenter because it is the point of intersection of the angular bisectors. While $\angle{ABC}$ and $\angle{ACB}$ is greater than $0$ , $\angle{BDB} = \angle{CDC} = 0$ so, they are not the angular bisectors.

It is not the orthocenter because it is the point of intersection of altitudes, and $\angle{BCA}$ and $\angle{ABC}$ is not equal to ${90}^°$ , so it is not an altitude.

It is not a centroid because it is the point of interesction medians and $C$ and $B$ are not the midpoints of $AC$ and $AB$ respectively. So, the answer is circumcenter.

Note :- In an isosceles triangle, the altitude is also its median, since AD is the altitude, it is also the median and thus the perpendicular bisector.