Step 1: Understanding the Concept:
In the calculation of eclipses and planetary disks, Indian mathematicians used algebraic variables. 'a' often stands for 'Ardh' (half) or a specific radius, and 'ka' stands for a full measure or a specific constant.
Step 2: Matching by Algebraic Proportion:
1. 2 ka (A): Since 'ka' is a radius-like measure, $2 \times ka$ represents the full diameter. Among the options, it corresponds to the Brihad-vyasa (Major Diameter). (A matches II).
2. 2 a (B): $2 \times a$ represents the full diameter of the smaller circle, Laghu-vyasa. (B matches I).
3. ka (C): The single unit 'ka' represents the radius, specifically the Brihad-vyasardha (Major Semi-diameter). (C matches IV).
4. a (D): The single unit 'a' represents the Laghu-vyasardha (Minor Semi-diameter). (D matches III).
Step 3: Verification:
Sequence: A-II, B-I, C-IV, D-III. This corresponds to Option (1).
Step 4: Final Answer:
The codes distinguish between the major and minor axes of the projected elliptical shadow or planetary disk.