Final answer:
The western half of Texas is characterized by the presence of mountains. Therefore, the correct option is c, mountains
Step-by-step explanation:
The geographic feature that is found only in the western half of Texas is the mountains. While Texas does have a coastline along the Gulf of Mexico, major rivers that run through the state, and some forests, the presence of mountains is exclusive to the western region. These mountains include the Guadalupe Mountains and the Davis Mountains.