ANSWER
The name of the segment inside the triangle is
[tex]altitude.[/tex]
EXPLANATION
The segment inside the large triangle is a line from one vertex of the large triangle that meets the the opposite side of the large triangle at right angle.
Any line from one vertex of a triangle that meets the side opposite to that vertex at right angle is referred to as the [tex]<b>altitude</b>[/tex] of the triangle.
Sometimes the altitude may fall outside the triangle.
Therefore the correct answer is option 2.
