The centroid of a triangle is found by constructing the
a)medians
b. altitudes
c. angle bisectors
d. perpendicular bisectors

The answer is A
A centroid of a triangle is the point where the three medians of the triangle meet. A median of a triangle is a line segment from one vertex to the mid point on the opposite side of the triangle.

The centroid of a triangle is found by constructing the median. The median is a line segment joining a vertex to the midpoint of the opposing side. Each triangle has 3 medians one of each is the vertex where all it intersects each other at the triangle's centriod.