Final answer:
Having states share a common marketplace provides several advantages, but one disadvantage is variations in product quality and safety standards.
Step-by-step explanation:
The correct answer is C) It can lead to variations in product quality and safety standards.
Having states share a common marketplace, also known as intra-state trade, provides several advantages such as promoting competition and innovation, simplifying regulatory compliance for businesses, and allowing for economies of scale in production and distribution. However, one disadvantage is that it can lead to variations in product quality and safety standards.
For example, if states have different regulations and standards for product quality and safety, it can create a challenge for businesses to meet all the requirements in each state. This can result in inconsistent product quality and safety for consumers.