Which of the following SCSI interfaces has the longest maximum cable length?

A.
SCSI-1

B.
Ultra SCSI.

C.
Fast SCSI.

D.
Ultra Wide SCSI.

Explanation:
SCSI-1 has the longest maximum cable length of 20 feet (6 meters) of the options given.
SCSI-2, which is also known as Wide SCSI also has a maximum cable length of 20 feet, however Ultra2 SCSI, Wide Ultra2 SCSI, Ultra160 SCSI, Ultra320 SCSI and Ultra640 SCSI have a maximum cable length of 40 feet (12 meters).

Incorrect Answers:
B, D: Ultra and Ultra Wide SCSI has the shortest maximum cable length of only 5 feet (1,5 meters).
C: Fast SCSI and Wide Fast SCSI have a maximum cable length of 10 feet (3 meters).
References:
Charles J. Brooks, Server+ Certification Exam Cram 2 (Exam SK0-002), QUE Publishing, Indianapolis, 2006, pp. 143-147.