Answer:
A researcher discovers a fossil of what appears to be one of the oldest-known multicellular organisms. The researcher could estimate the age of this fossil based on <em>the amount of uranium-238 in volcanic layers surrounding the fossil.</em>
<span>The spherical object within a cell that controls its activity is the nucleus. The nucleus is the spherical organelle inside the cells. The genetic material can be found within the nucleus. So, the genetic information of the cell is inside the nucleus and therefore the nucleus can the activity of the cell.</span>
Answer: A.They contain plants that purify water.