What could cause a significant difference between actual chain tension and the tension measured by the tensiometer?

Correct Answer: Option D — The chain contacting a chock or fairlead between the tensiometer and the lower swivel fairlead

Tensiometers measure line tension based on deflection. If the anchor chain contacts a structural member like a chock or fairlead between the measuring instrument and the lower swivel fairlead, frictional losses cause a false reading, creating significant measurement error.