What is the frequency of a wave? What unit is used to describe the frequency of a wave?

Which statement best describes the underground railroad? a.) it is a train that took slaves from the south to the north. b.) it is a business that harriet tubman founded to slaves become free. c.) it is a secret route that slaves took to escape from southern slave states to the north. d.) it is a road that slave owners disliked using for travel.

What are the biggest challenges facing the average american citizen today? explain.

What was the first major route to connect europe and asia