Answer:
d.wheat.
Explanation:
The wheat has a quality none of the other items has, which is are identitcal. Whice pizza, tennis racquets and even ype of garbage (organical, plastic, other) have a degree of differenciation that may derive in market segmentation. One of the condition for perfectly competitve market is that all osupplier offer the same good and it doesn't occur in the other options.
