Which of the following describe the ESCON?

A.
ESCON products at first attached storage devices.

B.
ESCON products initially locally attached workstations.

C.
ESCON products only attached to storage devices.

D.
ESCON products initially networked mainframe computers.

Explanation:
ESCON products originally networked mainframe computers, attached storage, locally attached workstations, and other devices together within local channels.
References:
Charles J. Brooks, Server+ Certification Exam Cram 2 (Exam SK0-002), QUE Publishing, Indianapolis, 2006, pp. 283-290.