Question

which contribution to the body of scientific knowledge is most recent?
the development of the lever
the discovery of the structure of dna
the discovery of electricity
the theory of evolution

Explanation:

The development of the lever dates back to ancient times. Electricity was discovered and studied over centuries with key developments in the 18th - 19th centuries. The theory of evolution was proposed by Charles Darwin in the 19th century. The structure of DNA was discovered by Watson and Crick in 1953, which is the most recent among these contributions.

Answer:

the discovery of the structure of DNA