Based on Pythagorean theorem, the length of the segment (x) indicated is: D. 3.4.
In Mathematics and Geometry, Pythagorean's theorem is an Euclidean postulate that can be modeled or represented by the following mathematical equation:

Where:
- a is the opposite side of a right-angled triangle.
- b is the adjacent side of a right-angled triangle.
- c is the hypotenuse of a right-angled triangle.
In order to determine the length of segment x, we would have to apply Pythagorean's theorem as follows;

x = 3.44 ≈ 3.4
Missing information:
The question is incomplete and the missing diagram is shown in the attached picture.