In the context of brain-tissue implants, what is unique about stem cells? they survive for extended periods outside of the body. they can develop into most types of human cells. they are insusceptible to the effects of plasticity. they transfer genetic information into human cells.

The correct answer is "they can develop into most types of human cells".

Stem cells are cells that are undifferentiated to what function they may serve, depending on the tissue where it will develop in to. In the context of brain tissue implants, these stem cells can develop into brain cells or nerve cells or neurons which comprises the functional brain tissue; this is clinically significant as neurons are not capable of replacing themselves if damaged.