Answer:
Option D.
Explanation:
The iron in the clay made the pottery red, is the right answer.
The clay for making pottery was available naturally throughout Greece. The Attic clay was the finest clay because it was rich in iron contents and thus gave an orange-red color with a flimsy shine when ignited. Therefore, people preferred using the Attic clay for pottery making and due to this most of the potteries of the Ancient Greek were red in color.
