Answer:
D. perpendicular.
Explanation:
We have been given a statement and we are supposed to choose the correct option to fill in the blank for our given statement.
Since we know that tangent is a line that touches the circle exactly at one point. This point is known as point of tangency. The tangent of the circle is perpendicular to the radius of the circle at point of tangency.
Therefore, the missing word from our given statement is perpendicular and option D is the correct choice.