Answer:
The correct answer is - option A. IKK.
Explanation:
In signal transduction or any other molecular biology process, the upstream or downstream is related to the molecular or cellular events that follow a mechanistic and temporal order.
In TNF signaling involved in cell survival pathway the TRADD- associated complex also is known as TNF receptor-associated death domain complex has a second messenger that activates temporally after the cell membrane receptor known as IKK signaling protein that help in numerous downstream pathways.
Thus, the correct answer is - option A. IKK.