In research on aging (both cellular aging and organismal aging), it has been found that aged cells do not progress through the cell cycle as they had previously. Which of the following would provide evidence that this is related to cell signaling?

The main reason is growth factor ligands do not bind as efficiently to receptors.

Initially, normal cells work efficiently on binding of enzymes, growth factors or ligands and cellular growth cycle runs effectively but with the passage of time, cellular aging or organismal aging can lead to decrease efficiency of cellular recepotors binding with the growth factor ligands gradually.