The above picture represents the different stages a cell goes through in its "lifetime." specific genes within the dna, called inhibitors, stop the cell cycle in g1 phase. this process to keep the dna unaltered and the cells dividing at the correct rate. if cells continue through the cell cycle, uncontrolled, may likely develop.

The answer is a tumor.  

Tumors are characterized by cells that have a mutation in their DNA that causes them to reproduce unregulated hence proliferate and do not form true tissues.  Inhibitors, called tumor suppressors, act like a ‘brake’ in the cell cycle. Cyclins, on the other hand, are the ‘gas pedal’ for the cycle. The right balance ensures that cell cycle is well regulated.   When the DNA is a cell is damaged, the tumor suppressors are rectruited to stop any further progress of the cell cycle and the cell undergoes apoptosis.

the answer for this question would be d. glaciers