Given here are four sentences. The first sentence is in the correct order, while the rest of the sentences are jumbled. Pick the option that gives the correct order.

A. Hans Christian Oersted, one of the leading scientists of the 19th century, played a crucial role in understanding electromagnetism. 

B. In 1820 he accidentally discovered that a compass needle got deflected 

C. when an electric current passed through a metallic wire, placed nearby.

D. Through this observation Oersted showed that electricity and magnetism were related phenomena.