The sand at Jason's feet appeared coarse, and he could see the individual grains of sand. However, the sand down the beach appeared to be much finer and less granular. This apparent difference in the sand may have partially resulted from the depth cue of
a. interposition.
b. light and shadow.
c. relative size.
d. texture gradient.

c. relative size

Explanation:

Jason has to look down the beach meaning the sand there is furtner from him. Since objects look smaller the further they are, the size he sees it is relative to the distance he sees it from.

Thus the answer is relative size.

what are the events?

first, the romans stayed isolated because they had to defend their own territories from neighboring cities that were harassing them, like the etruscans. second, once the romans managed to defeat their neighbors, and started to expand their territory, they started to build roads and bridges. finally, now that the romans have covered their territory with roads functioning as highways, they could mobilize their legions faster to assemble larger military units in a specific place