Isotonic, Hypotonic, and Hypertonic Solutions. Water moves readily across cell membranes through special protein-lined channels, and if the total concentration of all dissolved solutes is not equal on both sides, there will be net movement of water molecules into or out of the cell.
The correct choice is velocity=distance/time of v=d/t
Protoplanets are bodies or celestial objects which have the same size as the moon or a bit bigger. These bodies develop to eventually become planets. Therefore, the answer to this item is most likely letter D. outer planets.