A technician is troubleshooting a point-to-point fiber-optic connection. The technician is at a remote site and has no connectivity to the main site. The technician confirms the switch and the send-and-receive light levels are within acceptable range. Both fiber SFPs are confirmed as working. Which of the following should the technician use to reveal the location of the fault?
A. OTDR
B. Light meter
C. Tone generator
D. CSU/DSU