Answer:
Regulating protein agents.
Step-by-step explanation:
Cell division is a process in which one cell divides and gives rise to two or four cells depending on the type of cell division, i.e Mitosis or Meiosis.
Among the given option, Regulating protein agents is best suited because there are few regulating protein agents like Cyclin B and Cyclin.
The regulating protein agents they are talking about is certainly the cyclin, especially cyclin B. Cyclins donot exhibit any enzymatic activity but they have a major role in replication by stimulating other proteins and enzymes to stimulate cell division.During this process, different complex reactions take place and a Cyclin B / Cdk 1 complexes are formed and activated which lead to the entry of the cell into mitosis phase.
Hope it helps!