Final answer:
The lower bound of a triangle can be determined by its side lengths.
Step-by-step explanation:
The lower bound of a triangle can be determined by its side lengths. Therefore, the correct option is D) Side lengths. The side lengths of a triangle can determine its minimum possible perimeter. For example, if the three side lengths of a triangle are 5 cm, 7 cm, and 9 cm, then the lower bound for the perimeter of that triangle is 21 cm.