Differential survival and reproduction is best described by which term?

What do animals wth echolocation have in common other than echolocation

The vaccine in a flu shot contains weakened flu viruses. how does a flu shot work with the immune system? a. it destroys lymphocytes. b. it destroys macrophages. c. it activates macrophages. d. it activates lymphocytes.

Which ocean is on the eastern coast of north and south america? arctic ocean indian ocean pacific ocean atlantic ocean