Which contribution to the body of scientific knowledge is most recent?
a)the development of the lever
b)the confirmation of the double-helix structure of dna
c)the discovery of electricity
d)the theory of evolution

option a): level has been with us for a long time as early as at least 3rd century BC.,b) is a fairly recent development around 1950sc) electricity has been discovered in 17th century, so before b)d.) theory of evolution dates back to the middle of 19th century, so before b)therefore b) is the best answer.

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the answer to your question is b

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explanation: bc blah