Ineed this is for my k12 mws assingment sowhich of the following was not a new weapon or new method of warfare used during world war i u-boats airplanes poison gas artillery

Why was the u.s. annexation of hawaii delayed until william mckinley became president? a: the rebels who overthrew queen liliuokalani opposed u.s. annexation. b: the senate did not approve the treaty of annexation until mckinley entered the white house. c: supporters of the nationalist cause were in the majority in hawaii until 1898. d: mckinley’s predecessor, grover cleveland, refused to sign the treaty of annexation.