Hey y’all I really need some help here- What event might mark the end of a period?
A of the previous period
The fact that 100 million years had elapsed since the end
B A major geologic change
C The appearance of one new species
D The gradual drifting of the continents

is there a table of answers to choose from?

"the gulf of tonkin resolution in 1967".

the gulf of tonkin resolution (officially called southeast asia resolution, public law 88-408) is a law issued by the congress of the united states of america on august 7, 1964, in which president lyndon b. johnson was authorized1 to act in a comprehensive manner against the democratic republic of vietnam, which he accused of aggressions against us ships in the gulf of tonkin, where the resolution takes its name. the gulf of tonkin resolution is of historical importance because it gave authorization to the us president. lyndon b. johnson, without a formal declaration of war by congress, to use military force in southeast asia.