Final answer:
An interest group would benefit from opening an office in Austin primarily to influence state government, as it provides direct access to lawmakers and state agencies in the capital of Texas.
Step-by-step explanation:
The primary reason why it would be beneficial for an interest group to open an office in Austin is B) To influence state government. Interest groups aim to impact public policy and opening an office in Austin, the capital of Texas, places them at the heart of state decision-making.
The proximity to lawmakers, state agencies, and the governor's office increases the potential to lobby effectively and directly participate in the legislative process. This strategic location is essential because, as power shifted to state governments, states like Texas began to administer responsibilities originally under federal jurisdiction.