7-79I5 B
 A vessel is experiencing problems tracking the satellite in an Inmarsat-C SES while at sea. The problem is least likely caused by?
A. Extremely heavy rain/snowstorms.
B. Local RF interference by in-port cell phone or other radio systems.
C. Shadowing caused by an obstacle, such as a mast, between the SES antenna and the satellite.
D. The vessel is on the fringe of the coverage area of the satellite.
