Certain it is, that, some fifteen or twenty years after the settlement of the town, the wooden jail was already marked with weather-stains and other indications of age, which gave a yet darker aspect to its beetle-browed and gloomy front. the rust on the ponderous iron-work of its oaken door looked more antique than any thing else in the new world.
the author most likely include the words "darker aspect," "beetle-browed," "gloomy," and "ponderous" in order to?

a. impart a melancholy mood.
b. impart a mysterious mood.
c. establish a formal, civilized setting.
d. establish an old-fashioned setting.