What do contour lines represent on a map?

Food can come from sustainable or unsustainable resources. why has the united nations suggested that bugs could be a better source of food than animals like pigs or cattle?

Why the moon is not visible from earth during the new moon ?

Which statement explains what upwelling causes? a. upwelling causes tides to rise and fall. b. upwelling causes changes in the direction of currents. c. upwelling causes nutrients, minerals, and tiny organisms to rise. d. upwelling causes currents in the pacific ocean to change direction. i think the answer is c.