What is NOT a good rule-of-thumb when designing the placement of Erbium Doped Fiber Amplifiers (EDFA) in a ring?

What is NOT a good rule-of-thumb when designing the placement of Erbium Doped Fiber Amplifiers (EDFA) in a ring?

A.
Try to space the EDFAs evenly between transmitter and receiver

B.
Use a low noise, low gain EDFA for a pre-amp situation

C.
Use a high gain, high noise EDFA for a pre-amp situation

D.
For a 32 lambda system, try to avoid getting below -21 dBm input power for any lambda coming into an EDFA