C. Exactly one unique triangle exists with the given side lengths.
<u>Step-by-step explanation:</u>
A triangle consists of three sides, depending on the measurement of the sides, naming of the triangles can be varied.
If all the three sides are equal in length, it is said to be an equilateral triangle. Only one triangle can be formed using the measures of 7 in, 7 in, 7 in, that is all the three sides are same in measurement of 7 inches.
So, Exactly one unique triangle can be produced with the given side lengths.
