Final answer:
The main negative consequence of the Embargo Act initiated by Jefferson was that it caused significant harm to the American economy, with a large decline in commerce and an increase in unemployment. The correct option is d).
Step-by-step explanation:
The main unintended negative consequence of the Embargo Act instated by Thomas Jefferson was that it sadly hurt America's economy the most. The logic behind the Embargo Act was that by cutting off all trade, it would severely harm Britain and France to the extent that these nations would stop the seizures at sea.
However, the Act's actual impact was primarily felt by the American economy. The embargo prevented American merchants from selling their goods overseas, notably to Britain and France.
leading to widespread economic hardship including a significant increase in unemployment, bankruptcies, and a reported 75 percent decline in American business activity from 1808 to 1809. The negative impact of the embargo on American commerce was severe, leading to its eventual repeal in 1809. Option d) is the correct one.