What plant is identified by having clusters of bright red berries in the fall?

The plant characterized by clusters of bright red berries in the fall is indeed Sumac. Sumac is known for its vibrant red berries that grow in dense clusters, especially noticeable during the autumn. These berries are not only striking in appearance but also provide food for various birds and wildlife during the colder months.

Sassafras, while notable for its aromatic leaves and can produce small fruits, does not have the same striking berry clusters in the fall as Sumac. Arrowroot is primarily known as a tropical plant used for its starch, and it does not produce prominent red berries. Poison Ivy, on the other hand, is well known for its three-leaf structure and can produce small white berries, but these are not the bright red clusters associated with Sumac. Thus, Sumac stands out distinctly due to its colorful berry clusters in fall, making it the correct identification.