What Is Unusual About How the Tat Protein from HIV $\kappa$

What is unusual about how the tat protein from HIV activates transcription from the LTR?

A) It binds to the tat response element as RNA but not as DNA.
B) It binds directly to the cellular RNA polymerase II.
C) It binds to the reverse transcriptase enzyme and enhances its processivity.
D) It binds next to the TATA box and enhances binding of TBP to the LTR.
E) It inactivates the repressor of NF- $\kappa$ B so that this protein can bind to the LTR.