Which entity holds the highest authority in the state government of Texas?

The highest authority in the state government of Texas is held by the Texas Legislature. This is because the Legislature has the power to create and enact laws, control the state budget, and oversee state agencies, making it a critical component of the state's governance. While the Governor plays a significant role in executing laws and has considerable influence, particularly in matters of policy and administration, the ultimate authority resides with the Legislature which reflects the democratic principles of representative governance.

The State Supreme Court, while it has the final say on legal interpretations and state constitutional matters, does not create law but interprets it. The State Attorney General serves as the chief legal advisor and defender of the state's laws, but does not hold the highest authority in the government structure. Therefore, the correct identification of the highest authority in Texas government falls on the Texas Legislature.