The united nations decided to use a show of force against afghanistan because that country 1would not stop growing and producing opium 2was harboring the terrorist osama bin laden 3did not agree to economic sanctions against it 4had maliciously attacked the nation of pakistan

The correct answer here would be the second option here.

After the 9/11 attacks on the United States, the United States and the UN demanded that Afghanistan hand over the Taliban leader Osama Bin Laden.  Because of the Afghanistan's Taliban governments refusal, on October 7, 2001 the Operation Enduring Freedom was launched by the United Nations.