Plywood, while not the most pleasing wood to look at, has become an incredibly important building material in house construction. It is flexible, inexpensive, and strong. Its strength is due to layers of thin wood glued on top of each other with the grain of each layer making a right angle with the grain of the layer below it. This way of layering the sheets of wood makes plywood difficult to break. According to the passage, the arrangement of the layers of thin wood explains plywood's:A. strengthB. costC. attractivenessD. flexibility