Answer: C. 8
When we have two chords intersecting inside a circle, the products of the lengths of the segments are equal to one another. This means that for the given circle, we have the following:
10 * 4 = 5 * x
We can solve for x by multiplying 10 by 4, which is 40, and then dividing by 5, to isolate x, which is 8.
