Going through the choices, we will find that:
1- The line has no start point and no end point, it just extends infinitely from both directions. Therefore, it cannot be measured.
2- An angle can be measured only if we have more information to help us do the measurement. Since no information is given here, we cannot measure it.
3- A point cannot be measured. You can only locate it, but you cannot measure it.
4- A line segment has a start point and an end point. Therefore, we can measure its length.
5- A ray has a start point but no end point. We cannot measure it as we do not know where it ends.
Based on this, the right choice is:
D- Line segment
