Ross Needs to Move a Couch Up a Set of Stairs

Multiple Choice

Ross needs to move a couch up a set of stairs that turns a corner near the top.As he is thinking about the best way to go about this,he thinks about the position that the couch needs to be in when it turns the corner.That piece of information then anchors his decision about how to orient the couch at the bottom of the stairs.What does this example illustrate

A)  working backward
B)  representing the problem in a novel way 
C)  removing unnecessary constraints
D)  the trial-and-error approach