Al-qaeda’s main targets on september 11, 2001, were

boston, pennsylvania, and new york city.
pennsylvania and washington, dc.
new york city and washington, dc.
boston, new york city, and washington, dc.

New York City and Washington D.C

Explanation:

The 9-11 attacks hit New York City and Washington D.C. Specifically, WTC-1, WTC-2, WTC-7 and the South West side of The Pentagon. There was a flight that crashed in Pennsylvania however, I haven't any convicting evidence to prove one way or the other where it was going to go.

New York city and Washington DC.

Explanation:

9/11 attacks were the four attacks carried out by AL-Qaeda against US. It led to death of over 2700 persons and more than 24000 were injured.  Four passenger airlines were hijacked for the attack, two planes were crashed into the North and south towers of World trade centre that was located in Lower Manhattan (New York) and  47 storey Tower-7 also collapsed due to the debris of the north and south towers. The third plane was crashed in to the Pentagon and the Washington D.C was on the target of fourth plane but it crashed in Pennsylvania.

both include an amendment process.