Answer:
See below
Explanation:
By the Triangle Inequality Theorem, if given side lengths 
, 
, and 
, where 
 is the longest side, then 

Problem A
This set of side lengths creates a triangle since 

Problem B
This set of side lengths creates a triangle since 
, which is known as an equilateral triangle since all of its side lengths are equal to each other
Problem C
This set of side lengths creates a triangle since 
