What do the larvae of echinoderms indicate about the evolution of echinoderms?

Which beat describes the brain stem

Most animal cells membranes have proteins that pump ions out of the cell and potassium ions into the cell

The blue particles in this image are able to cross the cell membrane through simple diffusion. how will they be transported? outside the cell inside the cell o a. the substances will move directly across the membrane from outside the cell to inside the cell. b. the substances will move through channels in the membrane proteins from outside the cell to inside the cell. o c. the substances will move through channels in the membrane proteins from inside the cell to outside the cell. o d. the substances will move directly across the membrane from inside the cell to outside the cell.