Final answer:
Mirabeau Lamar is often credited as Texas's first historian due to his efforts in promoting and documenting the history of Texas during his presidency of the Lone Star Republic. The correct option is d.
Step-by-step explanation:
The individual considered Texas's first historian is not explicitly mentioned in the provided historical context. However, given the choices provided, Mirabeau Lamar is known for his significant contributions to Texas history, including extensive documentation and promotion of Texas history during his time.
He served as the second president of the Republic of Texas, and unlike some individuals like Sam Houston who were more politically or militarily influential, Lamar was more focused on the cultural and historical aspects, advocating for education and the arts which included recording the history of Texas. None of the other options are traditionally known as historians.
Therefore, while historical figures like Stephen F. Austin and Sam Houston played crucial roles in the Texas Revolution and the formation of the Lone Star Republic, it is Mirabeau Lamar who is often credited with having a deep interest in the history and culture of Texas.
Hence, Option d is correct.