Final answer:
The original Texas land grant documents known as protocols and testimonios are housed at the Texas General Land Office.
Step-by-step explanation:
The Texas land grants, originally documented in the form of protocols and testimonios, are of great historical significance. When it comes to locating these documents today, the correct answer is that they are housed at the Texas General Land Office. The General Land Office is responsible for managing public lands and serves as the steward of historical state documents. Despite the National Archives being a repository for historical records, these particular Texas land grant documents are located in the state-specific office that has jurisdiction over the management and preservation of such important state resources.