1. You have that two sides of a triangle have lengths of 6 and 13. Then, by the Triangle Inequality Theorem, you have:
a+b>c
a+c>b
b+c>a
3. Therefore, you have:
a=6
b=13
c<a+b
c<6+13
c<19
4. The difference between a and b should be lesser that c. Then
a-b<c
13-6<c
7<c
5. Therefore:
c=x
7<x<19
The correct answer is the option B: B. 7<x<19
