The Cretaceous-Tertiary extinction event, or the K-T event, is the name given to the die-off of the dinosaurs and other species that took place some 65.5 million years ago. For many years, paleontologists believed this event was caused by climate and geological changes that interrupted the dinosaurs' food supply.
It stemmed from the annexation of the Republic of Texas by the U.S. in 1845 and from a dispute over whether Texas ended at the Nueces River (the Mexican claim) or the Rio Grande (the U.S. claim).
The correct answer is C) China. The Open Door Policy, proposed by the United States in 1899. gave China the freedom to trade with all the countries equally. The first attempt of this policy did not go well, so when China opened for foreign businesses in 1978. it was called the second Open Door Policy.
