Which one of these exhibits gill slits at some stage of its development?

a. all echinoderms

b. all mollusks

c. all cnidarians

d. all chordates

Provide one reason why mitosis occurs.

Plz will mark! the diagram shows the positions of the sun, moon and earth during spring tides, when the high tides are at their highest and low tides at their lowest. what is it about these positions that causes these high and low tides?

Explain how scientists use geologic time to determine the age of landforms.