Based on the excerpt which of the following statements can be a third about the effect of the Louisiana purchase would have on the United States

1. Because of the high cost of the purchase the United States was struggling with the public debt
2. Because of the treaty French Cano longer pose a threat against the United States
3. Because of the purchase of territory Americans can now legally start selling regions in the west
4. Because of its ratification the treaty Congress confirmed that presidents have the power to purchase the land

To determine which statement can be a third about the effect of the Louisiana Purchase on the United States, we need to analyze the provided options.

1. "Because of the high cost of the purchase, the United States was struggling with public debt."
This statement does not directly discuss the effect of the Louisiana Purchase on the United States, but rather focuses on the financial implications of the acquisition. It may be an accurate statement, but it does not directly address the effect on the country.

2. "Because of the treaty, France can no longer pose a threat against the United States."
This statement refers to the Treaty of Paris, which ended French control over the Louisiana Territory and removed the potential threat of French occupation or intervention. This could be a potential effect of the Louisiana Purchase on the United States.

3. "Because of the purchase of territory, Americans can now legally start selling regions in the west."
This statement suggests that the acquisition of the Louisiana Territory allowed Americans to legally start selling land in the western regions. This statement addresses the potential economic impact of the purchase.

4. "Because of its ratification, the treaty confirmed that presidents have the power to purchase land."
This statement discusses the ratification of the Louisiana Purchase treaty by Congress, highlighting the confirmation of the president's power to purchase land. This addresses the constitutional implications of the purchase.

Based on the analysis, statements 2, 3, and 4 all address different effects of the Louisiana Purchase on the United States.
Ultimately, the answer would depend on the specific context or information given in the excerpt.