Which of the following can be considered a physical barrier to trade?

Choosing "No sea ports" as the correct answer emphasizes the impact of physical infrastructure on trade capabilities. The absence of sea ports directly limits a country's ability to engage in maritime trade, which is critical for international commerce. Without access to sea ports, a nation cannot efficiently import and export goods, leading to significant barriers in global trade. This lack of access not only affects the movement of products but also restricts the flow of resources, which can hinder economic growth and development.

In contrast, economic sanctions represent political or economic restrictions imposed by one nation on another, often to influence behavior or policy. High tariffs are a form of trade barrier that increases the cost of imported goods through taxation, which can deter trade but is not a physical limitation. Currency fluctuations involve changes in exchange rates, affecting pricing and profitability in trade but are also not physical barriers to trade. Each of these other options indicates different types of barriers, but the absence of sea ports is uniquely tied to the physical capabilities necessary for trading activities.