Final answer:
A seventh chord in third inversion is indicated by the order of the 5th, 7th, root, and 3rd notes.
Step-by-step explanation:
In music theory, a seventh chord in third inversion is built by arranging the notes in the order of the 5th, 7th, root, and 3rd. So, the correct option is 3) 5th, 7th, Root, 3rd.