An Important Transcription Factor Activated by Antigen Receptor Signaling in Lymphocytes

An important transcription factor activated by antigen receptor signaling in lymphocytes is an NF $\kappa$ B heterodimer of the two subunits, p50 and p65Rel. Defects in the I $\kappa$ B-kinase complex (NEMO) or mutations in I $\kappa$ B that prevent its phosphorylation interfere with NF $\kappa$ B activation and result in severe immunodeficiency diseases. This is due to the important function of:

A) NEMO in targeting p50:p65Rel for ubiquitination and degradation
B) NEMO in ubiquitinating I $\kappa$ B causing its release from NF $\kappa$ B
C) I $\kappa$ B in blocking the DNA binding activity of NF $\kappa$ B
D) I $\kappa$ B as a chaperone to promote NF $\kappa$ B nuclear localization
E) NEMO in phosphorylating I $\kappa$ B inducing its degradation, thereby releasing NF $\kappa$ B