The correct answer to this open question is the following.
One goal of U.S involvement in the war in Afghanistan was to eliminate the terrorist cell led by Osama bin Laden, after this cell made itself responsible for the terrorist attacks of September 11, 2001.
One challenge of U.S involvement in the war in Afghanistan was that the Afghans knew their territory very well. That is why President Bush ordered an air raid over Afghanistan, with the support of Great Britain.
One goal of U.S involvement in the war in Irak was to capture and kill Irak's dictator Sadam Hussein. One challenge of U.S involvement in the war in Irak was to demonstrate that Sadam Hussein had arsenals of weapons of mass destruction. The US troops never find these weapons.
I'm sure the answers d, because it would help way more than the other options you'd want to know first hand what happen the only way to do so is to speak to those who fought in the war.
