On a semisubmersible drilling unit, decreasing riser tension increases __________.

Correct Answer: Option B — GM

Marine riser tension acts as a downward force applied at the upper deck level. Decreasing this top-weight load lowers the vertical center of gravity (KG). Since metacentric height (GM) is the difference between KM and KG, reducing KG directly increases GM, improving initial transverse stability per standard stability principles.