The answer is A. - Prokatyotic cells lack a defined nucleus while eukaryotic cells do have one :) I loved learning about the cells in biology! But I noticed your question is worded a little differently so the nucleus would be the one thing a eukaryotic cell has that a prokatyotic cell does not...
There are multiple energy source in the ocean. The one thats probably the most common one are Dams. Although Dams can cause some serious flooding. Another one is Tidal energy. Tidal energy is something that turns the energy of tides into energy through Kinetic motion.<span />
The older the Earth's crust, the denser it is.
Elements are pure substances made up of atoms
