A 2.0m-tall sculpture stands 6.0m in front of a vertical plane mirror mounted on a wall. A visitor whose eyes are 4.0m from the mirror wants to see the entire height of the sculpture in the mirror at once. What is the minimum vertical length of the mirror that will allow this?
(a) 0.67m
(b) 0.80m
(c) 1.33m
(d) 1.0m