Identify a secant that contains a diameter of M

AC

Explanation:
A secant is a line that touches two points on the circles edge. Unlike a chord, a secant will go beyond the circles edge. By that definition, AD and AM are eliminated. The secant must also go through the point M since that is the midpoint. The diameter always goes through the midpoint. AB doesn’t go through M. However, AC does successfully meet all the requirements. It has two points on the circle, the line goes farther than the circles edge, and the line passes through the point M.