How Did Optical Illusion Mislead Early Visual Observers of Mars

How did optical illusion mislead early visual observers of Mars?

A) Apparent movement of surface features, because of fluctuations in images when viewed through Earth's atmosphere, were interpreted as evidence for moving life-forms or Martians.
B) Volcano and rock structures were seen as eye shaped and face like and were interpreted as having been made by intelligent beings to indicate their presence.
C) Moving areas of obscured detail on the planet were interpreted as massive flash floods rather than dust storms.
D) Chance alignments of faint, dark features looked like canals whereas darker areas, when viewed against the orange-red surface, were interpreted as vegetation.