Final answer:
Saint-Domingue was one of the richest colonies in the Caribbean due to its use of slave labor to produce sugar and coffee crops for the global market, garnering extensive profits for the French economy. The correct answer is option C.
Step-by-step explanation:
Saint-Domingue was one of the richest colonies in the Caribbean primarily because of C. It used slave labor to grow crops for the world market. The colony's wealth was generated from the production of cash crops such as sugar and coffee, which were labor-intensive and required a large workforce. As the native labor pool was insufficient for the scale of plantation agriculture that developed, the French colonists imported hundreds of thousands of African slaves to toil on the plantations. This brutal exploitation resulted in immense profits for the French economy, with Saint-Domingue contributing significantly to the imported sugar and coffee in Europe. At the peak of its wealth, the colony of Saint-Domingue had the highest sugar production in the Caribbean, greatly surpassing that of other colonies.