What effect do load coils in a telephone line have on DSL service?

What effect do load coils in a telephone line have on DSL service?

A.
Load coils cause low trained rates for ADSL (CAP or DMT), but do not degrade SDSL, SHDSL, or IDSL transmission.

B.
Load coils in the telephone line can prevent any DSL modem from training up to an ATU-C port.

C.
Load coils cause low upstream rates, but do not degrade downstream rates.

D.
Load coils cause low downstream rates, but do not degrade upstream rates.

E.
Load coils cause low trained rates for SDSL, SHDSL, or IDSL, but do not degrade ADSL (CAP or DMT) transmission.