Which technique uses sound waves to measure the depth of the ocean floor?

The persian wars started when emperor darius i began an invasion of greece. what caused darius to decide to attack greece? a. greek pirates had raided persia's merchant ships and coastal towns. b. greek armies had attacked and taken over land that belonged to persia. c. greek city-states had supported rebellions in the persian empire. d. greek leaders had declared independence from the persian empire.

What was piaget's explanation as to why preschool-age children in the preoperational stage make errors on tasks requiring conservation? a) preschool children's tendency toward centration prevents them from focusing on other relevant features of a situation b) preschool children have not yet developed numerical understanding; therefore, different amounts are meaningless c) preschool children's neural-visual network is not fully matured d) preschool children have not lived long enough and accrued enough experience to know the difference between quantities

Napoleon once said that "a revolution is an idea which has found its bayonets." what was napoleon's take on the french revolution? a. he opposed it because he supported the ideas of king louis xiv. b. he supported it and campaigned for a similar revolution in italy. c. he opposed it because he disagreed with the use of violence against french citizens. d. he supported it and to spread revolutionary ideas in corsica.