The area bounded by diameter and the semicircle is called
A. minor segment
B. major segment
C. semicircular region
D. perimeter

Hint: To solve this type of problem we have to know the basic definitions of geometry and the geometries of the circle. The definition of diameter, segment, etc. We will draw a picture and from that, we will say to which region it belongs.

Complete step-by-step solution -
A circle is the locus of all points equidistant from a central point.
A circle is a plane figure bounded by one curved line, and such that all straight lines drawn from a certain point within it to the bounding line, are equal. The bounding line is called its circumference and the point is its center.
A semicircle is a one-dimensional locus of points that forms half of a circle.
Now we will draw a circle with diameter line as shown,

From the figure, we can clearly say that the area bounded by the diameter is the semicircular region.
The diameter divides the circle into two semicircles.
Therefore the answer is option C.

Note: This is a direct problem which can be solved by knowing the definition. A line segment which divides the circle into two unequal parts is called the chord. The area of the semicircle is half the area of the circle.