Which system produces ATP when engaging in intense, short-duration activities without oxygen?

The anaerobic system is the correct choice because it is specifically designed to generate adenosine triphosphate (ATP) during high-intensity, short-duration activities where oxygen availability is limited. This system primarily relies on phosphocreatine and glucose to produce energy quickly without the need for oxygen through processes such as the ATP-PCr system and anaerobic glycolysis. These pathways enable the body to maintain performance levels during activities like sprinting or lifting heavy weights, where rapid bursts of energy are required.

In contrast, the aerobic system depends on oxygen to produce ATP and is more suited for sustained, lower-intensity activities such as long-distance running or cycling. The energy system and metabolic system are broader terms that do not specifically refer to the generation of ATP in the absence of oxygen, and thus do not accurately identify the mechanism being utilized during intense, short efforts.