For starters, ENIAC was as big as a room and had many parts that don't even exist nowadays. It was operated by humans and broke down often. Information processing was a tedious and a difficult process. Modern components enable much faster data travel, fewer opportunities for the thing to break down, and an easier access for people to process data.
Metals is the right answer.
They are solids with a repeating pattern. then answer is D.
In the voltage-gated channels, the stimuli is a change in the voltage across the membrane.
In mechanically gated channels the stimuli is a mechanical stress.
In ligand-gated channels the stimuli is the binding of a ligand:ion or molecule that binds to a metal atom.
