The answer is A. Pollutant
I think what happens is that the Cyclin component of the MPF is degraded. MPF or mitosis promoting factor, consists of two important cell cycle regulatory protein called the cyclin and cyclin dependent kinases (CDK). The cdk and the cyclins are the major control switches for the cell cycle, causing the cell to move from G1 to S or G2 to M.
Nucleus. Cytoplasm . Ribosome . Endoplasmic reticulum . Golgi body . Mitochondria . Lysosome
Cell membrane
the following parts of a cell.
Structure
The volcanoes may be dormant or not as active. Only very active volcanoes will be known for erupting a lot.