Explanation:
We need to establish their definitions
From definition, the median of a triangle is the the line joining a vertex to the midpoint of the opposite side
From the diagram, B is a vertex and a line passes through it to the midpoint of the opposite side AC
BD is the median in this case
By definition, an altitude of a triangle is a line that passes through a vertex and perpendicular to the base of the opposite side.
From the diagram , AC doesnot pass through a vertex and perpendicular to the base of the opposite side.