Final answer:
Option (a), To legally open a dog grooming business, Penny should adhere to city ordinances, which include local laws and zoning regulations relevant to her business.
Step-by-step explanation:
Penny is investigating the requirements for legally opening a dog grooming business in her city. The regulations that would govern the establishment and operation of her business are most likely city ordinances. These are local laws that define zoning regulations, business licensing, health standards, and other municipal codes that businesses must adhere to.
The other options provided, such as national parks regulations, international treaties, and federal aviation laws, are not relevant to a local dog grooming business. Penny will also need to consider other aspects like governmental restrictions, benefits of owning property, and how financial institutions might help her with business operations.