Navy use sonar method to locate the position of submarine under water .the waves used in sonar are

Answer me pls is an algorithm that has been coded into something that can be run by a machine.

11. is the ability to understand how another person is feeling. a. authority b. sympathy c. empathy d. taking a stand

Which demographic challenge is europe currently experiencing? a. an aging and decreasing population b. a baby boomc. an unequal distribution between males and females d. a large group of teenagers moving through the school system(i chose a but i'm unsure)