Final answer:
The senator is using the infant industry argument to support their argument in favor of the trade restriction on microprocessors. Hence, the correct answer is option 3.
Step-by-step explanation:
The senator is using the infant industry argument to support their argument in favor of the trade restriction on microprocessors. The infant industry argument suggests that protecting new industries for a limited time can help them become established and successful in the long run.
By blocking imports for a limited time, the domestic industry has the opportunity to develop the necessary skills, technology, and economies of scale before facing international competition. This protects the industry from unfair competition and allows it to grow and compete on equal terms in the global economy.