Which is a Physical layer standard for transmitting data over fiber optics lines?

A.
SDD

B.
SONET

C.
Frame relay

D.
X.25

Explanation:
Synchronous Optical Network (SONET) is a standard for fiber optic
cabling and uses self-healing network rings. SONET describes the interfaces that can
be used over fiber lines and the signaling that must be employed. SONET works at the
Physical layer of the OSI model.