Which of the following statements about figures associated with circles is true?
a. a secant intersects a circle in three points.
b. a secant is a tangent.
c. a diameter is a chord.
d. a tangent includes a segment called a chord.

A secant is a line that intersects a circle at 2 points >>>> A is wrong
A tangent intersects a circle at one point and is perpendicular to the circle >>>> B is wrong
A diameter and a chord is both a line segment that intersects a circle into 2 curves >>>> C is correct
A tangent intersects a circle only at one point >>>> D is wrong

The answer is X^2+10xi+6x-16+30i