Answer:
The correct answer is option A, that is, letters to tuna companies.
Step-by-step explanation:
The application of dolphin-safe nets for catching tuna began due to letters sent to the tuna companies. The application of dolphin-safe fishing nets came into force as many dolphins were drowning in nets that were used to catch yellowfin tuna fishes. The approach was a novel plan, which the United States had started in order to elevate the shortage of tuna taking place in the country.