89．無線電高度表，其天線到接收機的同軸饋線 coaxial cable：
(A)可調整長度‧The cable length is non-critical you can adjust and cut.
(B)不可調整‧The cable length is critical you cannot cut and adjust.
(C)無關‧There are nothing to do the system.
(D)以上皆非‧None above.