False (option B)
Step-by-step explanation:
To answer the question, we will be using diagrams
An altitude is a line that passes through a vertex and it's perpendicular to the side opposite this vertex.
A circumcenter is a point where perpendicular bisectors of the sides of a triangle meet.
From our diagram, we see that the lines do not have to be an altitude as altitudes are lines that pass through the vertex. The perpendicular bisectors here do not pass through the vertex.
The statement the circumcenter is the point shared by the altitudes of a triangle is false