To What Is the NLS - Protein Cargo - Importing $\alpha$

Multiple Choice

To what is the NLS - protein cargo - importing $\alpha$ / $\beta$ complex thought to bind when it seems to dock to the outer surface of the nucleus near the nuclear pore complex?

A) the torus
B) the outer ring of the nuclear pore complex
C) the inner ring of the nuclear pore complex
D) cytoplasmic filaments that extend from the outer ring of the nuclear pore complex
E) the transporter