Final answer:
The subject of this question is History at the Middle School level, the correct answer is Rene Robert Cavelier, and he explored and established missions in East Texas.
Step-by-step explanation:
The subject of this question is History at the Middle School level. The question asks about a French explorer who helped establish missions and a presidio in East Texas.
The correct answer is Rene Robert Cavelier who was also known as Sieur de La Salle. He explored the Mississippi River and claimed the Louisiana Territory for France.
Keywords: History, Middle School, French explorer, missions, presidio
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