Final answer:
Brandon cannot reach his dad at Windows on the World because it was the name of the restaurant that was destroyed in the September 11 attacks when the North Tower of the World Trade Center collapsed.
Step-by-step explanation:
Brandon cannot reach his dad at Windows on the World because this refers to the restaurant that was located on the top floors (106th and 107th) of the North Tower (One World Trade Center) of the original World Trade Center in New York City, which was destroyed in the September 11 attacks of 2001. Following those tragic events, the restaurant, along with the rest of the buildings in the complex, was completely obliterated when the towers fell. This means that Brandon would be unable to make contact with anyone at that location as it no longer exists. Brandon cannot reach his dad at Windows on the World because the World Trade Center, where the restaurant was located, was destroyed in the September 11, 2001 terrorist attacks. The attacks resulted in the collapse of both towers, causing enormous loss of life, and the destruction of many businesses, including Windows on the World.