If the creators of the robot wanted to provide evidence that it is alive, which of the following properties would be best to use as evidence?

• A. The robot can move its limbs.
• B. The robot can respond to stimuli.
• C. The robot can store energy in a battery.
• D. The robot must be bathed in a liquid medium to provide nutrition for its cells.

Answer: (D)

Evidence that something is alive comes from its ability to sense the environment and respond to changes in a purposeful, regulated way. A robot can be programmed to move or to store energy, but those are just mechanical capabilities and don’t prove life. Requiring a liquid nutrient bath describes biological metabolism tied to cells, which doesn’t apply to a machine lacking cells. The strongest indicator here is the ability to respond to stimuli—an adaptive, sensor-driven change in behavior that suggests a living-like processing of information rather than a fixed, preplanned action.