Which informal term describes a drilling rig fitted with long support legs that can be raised or lowered independently of each other?

• A. Drilling Rig
• B. Platform Rig
• C. Semi-Submersible Rig
• D. Jackup Rig

Answer: (D)

The key idea here is a mobile offshore drilling unit that gains stability by extending tall legs to touch the seabed and can raise or lower those legs independently. That setup defines a jackup rig. Drilling rig is too general and could refer to many types of rigs, not specifically legged and elevating. A platform rig often implies a fixed or platform-based arrangement rather than legs that actively extend and retract. A semi-submersible rig relies on buoyancy and a floating hull rather than independently adjustable legs touching the seabed. Therefore, the informal term describing a rig with long, independently adjustable legs is jackup rig.