Answer:
C) They explored the Mississippi Delta River
Step-by-step explanation:
The most common feature in De Soto, La Salle, and D'Iberville's expedition was that they explored the Mississippi Delta River.
The Mississippi Delta river is located in the Mexico Gulf, at the confluence of the Mississippi river, Louisiana Southeastern United. It is delta dominated river which is influenced by the largest network of water systems in the North America.
Therefore, the correct answer is option C)