c) is the correct option
Step-by-step explanation:
Inhibition of Cdk activity occurs by Cdk inhibitory protein (CIPs)
- A group of specific proteins called CIPs binds with active cyclin Cdk complex and cause their inactivation
- Activated protein retinoblastoma (p53)act as transcriptional factor and induce synthesis of Cdk inhibitory proteins p21CIPs
- p21CIPs is a Cdk inhibitory protein that binds and inhibit the activity of G1 Cdk cyclin complex as a result cell cycle arrest in G1 phase