To prevent the riser system from buckling under its own weight, upward tension is provided by the __________.

Correct Answer: Option C — riser tensioning system

The riser tensioning system applies constant upward force to the marine riser string. This tension is critical to prevent the riser from buckling under its own weight or due to environmental forces like currents and vessel motion, ensuring the riser remains straight and connected to the subsea wellhead.