Step 1: Arrange the terms by size
Chari is the smallest unit of foot work. Above it comes the Karana, and above that comes the Khanda. Aharya is not a movement term.
Step 2: Find the unit that Charis build
Charis join together with hand gestures and body stance to make a Karana, the first full dance unit in the Natya Shastra.
Step 3: Rule out option 1
Mandala describes a body posture or a pattern of positions, not the unit that Charis make by joining.
Step 4: Rule out option 3
Khanda is a chain of Karanas, so it sits one level above the answer and cannot be the unit made directly from Charis.
Step 5: Rule out option 4
Aharya is about dress and make up, so it cannot come from combining steps.
Final Answer:
Option 2, Karana, is correct. \[\boxed{2}\]