Based on this text, what methods does Magnus use to find the truth about the nature of comets?

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.