What do you believe the quote “Necessity is the mother of invention” means?

Alarge increase in gas prices creates a demand for cars with good gas milage. it takes months for car companies to make these cars. how do you describe this market for cars

Which of the following was a key accomplishment of the people of songhai? a. they had a strong military and became the largest empire in west africa. b. they established a center of islamic scholarship. c. they worked with iron and prospered from the gold-salt trade. d. they dominated in the trade of ivory, enslaved people, and animal skins.

The primary purpose of a certificate of confidentiality is to: allow law enforcement to investigate abuse cases.protect researchers from disclosing conflicts of interest.prevent subjects from knowing the purpose of a study.protect identifiable research information from compelled disclosure.