What Causes the Changing Dark and Light Features Visible on the Martian

Multiple Choice

What causes the changing dark and light features visible on the Martian surface from Earth?

A) seasonal growth of vegetation
B) the flooding of the network of canals from seasonal polar ice melting
C) lava fields, similar to those found on the Moon
D) highly cratered and eroded areas that are frequently covered and uncovered by dust
E) huge storms like those on Jupiter with winds that often reach speeds of hundreds of kilometersper hour