In several nineteenth-century paintings the marble buildings of the Acropolis in Athens are portrayed as being reddish, but the buildings do not now appear reddish. The marbles natural color cannot have changed since the nineteenth century, so the paintings must not be showing the color of the buildings as they actually appeared. Which of the following, if true, most seriously undermines the argument above？

A. The Acropolis can be clearly seen from virtually any location within the city of Athens.
B. Tiny plants called lichens living on marble can cause the marble to appear reddish.
C. Many nineteenth-century artists strove for true-to-life accuracy in every detail of their paintings.
D. Some types of marble are naturally reddish, whereas other types are greenish or white.
E. Not all nineteenth-century paintings of the Acropolis show the marble buildings as being reddish.