Final Answer:
The Spanish adventurers call the estuary near their campsite the "Bay of Horses" because they are killing, roasting, and eating their horses, as indicated by option C.
Step-by-step explanation:
The naming of the estuary as the "Bay of Horses" is explained by the fact that the Spanish adventurers are engaging in the practice of killing, roasting, and consuming their horses. This is evidenced by the specific mention of option C. In historical contexts, such expeditions often faced challenges of survival, and resorting to consuming their horses suggests a critical need for sustenance. Naming the estuary in this manner reflects the pragmatic and harsh realities of the explorers' circumstances.
The consumption of horses was a desperate measure undertaken in situations where food supplies were scarce, and survival was at stake. In this context, the Spanish adventurers resorted to using their horses as a source of sustenance, leading to the association of the estuary with this practical and vital aspect of their expedition. The choice of naming reflects the challenges and hardships faced during exploratory journeys and the pragmatic decisions made in the pursuit of survival.
In conclusion, the name "Bay of Horses" is directly linked to the pragmatic act of killing and consuming horses by the Spanish adventurers. This naming choice captures a moment of survival and resourcefulness in the face of challenging circumstances during their expedition.