The principal writer of the Texas Declaration of Independence was George Childress. To arrive at this answer, we can eliminate some of the other options. Austin refers to Stephen F. Austin, who played a significant role in Texas's fight for independence, but he was not the principal writer of the declaration. Bowie refers to James Bowie, a famous Texan who fought in the Texas Revolution, but he also was not the principal writer. De Zavala refers to Lorenzo de Zavala, who served as the vice president of the ad interim government of the Republic of Texas, but he was not the principal writer of the declaration either. That leaves us with the correct answer, Childress. George Childress was one of the five men appointed to draft the declaration, and he is credited as the primary author.
