Which Highland Dance style is associated with the use of swords on the ground?

The Sword Dance is the style associated with the use of swords on the ground, making this the correct answer. This traditional Scottish dance involves the dancer performing intricate footwork around and over two crossed swords placed on the floor, symbolizing the importance of precision and balance. The dance is steeped in history and was originally performed as a way to demonstrate a warrior's skill and agility.

In this style, the dancer must execute specific movements that show not only technical prowess but also an understanding of the rhythm and musicality that accompany the dance. The visual element of dancing around the swords adds a dramatic flair and highlights the cultivation of grace and discipline inherent in Highland Dancing.

The other styles listed do not incorporate swords as part of their dance structure. The Highland Fling is a lively solo dance known for its powerful leaps, the Reel is typically a social dance that involves flowing movements, and Seann Triubhas focuses on the rhythm and timing without the utilization of swords. Hence, the Sword Dance stands out distinctively due to its unique feature of integrating swords onto the dance floor.