Final answer:
Quantum entanglement is considered an active link between particles because it enables the instantaneous correlation of their properties, even when they are separated by large distances.
Step-by-step explanation:
Quantum entanglement is considered to be an active link between particles because it allows for the instantaneous correlation of their properties, even when they are separated by large distances. When two particles become entangled, their states become intertwined, meaning the measurement of one particle's state is immediately reflected in the state of the other particle. This instantaneous connection between entangled particles is why quantum entanglement is referred to as an active link.