<span>C. Silurian </span>The first jawed fishes and uniramians (like insects, centipedes and millipedes) appeared during the Silurian (over 400 million years<span> ago). First vascular plants (plants with water-conducting tissue as compared with non-vascular plants like mosses) appear on land (Cooksonia is the first known).</span>
From the brightness of the light of course. If the brightness is increasing it means the the light source is approaching and if the brightness is decreasing it means the light source is leaving.
