Step 1: Understanding Vaiśeṣika Theory of Atomism.
The Vaiśeṣika school of philosophy in India is known for its atomic theory, where it categorizes all substances into atomic and non-atomic elements. According to this theory, the basic elements of the world include earth, water, fire, air, and ether. However, ether (ākāśa) is considered to be non-atomic because it is an infinite medium, unlike the other four elements, which are composed of atoms.
Step 2: Analyzing the options.
- (A) Ether (\={a}kāśa): This is correct because ether is considered non-atomic in Vaiśeṣika theory.
- (B) Earth (pṛthvī): Earth is atomic in Vaiśeṣika theory.
- (C) Fire (tejas): Fire is atomic in Vaiśeṣika theory.
- (D) Air (vāyu): Air is atomic in Vaiśeṣika theory.
Step 3: Conclusion.
The correct answer is (A) Ether (\={a}kāśa), as it is not considered atomic in the Vaiśeṣika theory.