A contract between a company in the United States and one in China contained a clause that stated: "If an event happens which is extraordinary and out of the control of the parties such as a strike, act of God, fire, accident, or transportation difficulties, then the affected party shall be relieved of its obligations under the contract." This type of clause is a(n):

As of my last knowledge update in January 2022, the most widely accepted theory about early human migration to the Americas is the Bering Land Bridge or Beringia Theory. According to this theory, it is believed that the first humans to populate the Americas migrated from Asia to North America by crossing a land bridge that once connected Siberia (in present-day Russia) to Alaska during the last Ice Age.

Key points of the Bering Land Bridge Theory include:

1. Land Bridge Existence: Approximately 15,000 to 20,000 years ago, during the Pleistocene epoch, sea levels were lower due to the accumulation of glacial ice. This exposed a land bridge, known as Beringia, connecting Asia and North America.
2. Migration Route: It is proposed that early human populations, often referred to as Paleo-Indians, crossed this land bridge and gradually migrated southward into North America.
3. Timing of Migration: The migration is thought to have occurred in multiple waves, with the initial movements potentially starting around 20,000 years ago and continuing for several thousand years.
4. Archaeological Evidence: Archaeological evidence, including stone tools and other artifacts found in North and South America, supports the idea of a gradual human migration from Beringia into the Americas.
5. Genetic Evidence: Genetic studies, including analysis of mitochondrial DNA and Y-chromosome markers, have provided supporting evidence for a common ancestry among Native American populations and certain Asian populations.

While the Bering Land Bridge Theory is widely accepted, there is ongoing research and discussion in the scientific community, and additional evidence may contribute to refining our understanding of the timing and routes of early human migration to the Americas. It's important to check for updates from scholarly sources for the latest information on this topic.