What volcanoes form on a divergent plate margin

Which of there factors contributed most to us westward expansion in the second half of the nineteenth century?

Which of these is least likely to be an adaption? a. a mouse digs a hole to hide from predators. b. a snake bites its prey to deliver it deadly venom. c.a jackrabbit has large ears that it release body heat. d.a parrot learns to say its owner's name.

In 1933 the 21st amendment was added to the u.s. constitution, allowing for the manfacture, transportation, and sale of alacoholic beverages in the united states. why was this amendment needed?