ISI marked goods are always pure.

The correct answer is C. unmixed.

ISI marked goods are always pure because they have been tested and certified by the Bureau of Indian Standards (BIS). The BIS is a government body that sets standards for goods and services in India. ISI marked goods must meet these standards in order to be sold in India.

The other options are incorrect because they do not accurately describe ISI marked goods. Clear goods are goods that are transparent or translucent. Fresh goods are goods that are not spoiled or rotten. Clean goods are goods that are free of dirt or debris.

ISI marked goods are not always clear, fresh, or clean. However, they are always pure.