Final answer:
The addition of glass windows is the European influence upon traditional Azande homes. The correct option is C.
Step-by-step explanation:
The European influence upon traditional Azande homes can best be seen in the addition of glass windows.
Traditional Azande homes typically had thatched roofs, mud floors, and walls made of either mud or wood.
However, through European influence, glass windows were introduced to Azande homes, providing a new feature that allowed natural light to enter the interior spaces and improved ventilation. Glass windows are not a traditional element of Azande homes but are a result of European architectural influence.
Hence, Option C is correct.