Final answer:
In one second, a lipid in an artificial bilayer may diffuse as far as 2 nanometers, equivalent to the width of a DNA double helix.
Step-by-step explanation:
The question seeks to understand the diffusion distance of a lipid within an artificial bilayer in one second. Lipids in a synthetic bilayer can move quite rapidly, yet they do not tend to cover extremely large distances instantly. Considering the sizes mentioned in the question, option A, which suggests a distance of 2 nanometers, is a realistic estimate of the distance a lipid could diffuse within a second in an artificial bilayer. This distance roughly corresponds to the width of a DNA double helix. To clarify, 2 microns, as suggested in option B would be quite a large distance for a lipid to move in such a short time, and 500 microns, the length of a typical amoeba, as referenced in option C, is far too great for such a brief diffusion period.