Final answer:
Cabeza de Vaca's journey was significant as it marked one of the earliest European explorations of Texas, paving the way for further Spanish exploration and conquest in the region.
Step-by-step explanation:
The significance of Álvar Núñez Cabeza de Vaca's journey in Texas history is noteworthy for its role in early European exploration of the region. Option a) His journey marked the first European exploration of Texas, accurately captures the essence of his significance. While he did not discover gold nor established a permanent settlement, Cabeza de Vaca's expedition was among the earliest forays into the Texas interior, leading to further Spanish interest and eventual conquest of the area. His journey, along with others following the initial discovery by Columbus, contributed to Spain's extensive efforts to explore and claim lands in the Americas.