Which novel was Sinclair Lewis's closest use of the realistic method? Arrowsmith
Babbitt
Main Street

Arrowsmith.

Explanation:

Sinclair Lewis's novel Arrowsmith revolves around the life and experiences of a medical scientist, Martin Arrowsmith. Written during the late 19th century after the medical education reforms and deals with the culture of science. It contains the realistic natures and life of someone in the medicinal scientific studies through the life of Arrowsmith.

Whereas, the other two novels Babbitt and Main Street are satirical novels that satirize American culture and society where the characters live. These two books deals with the pressures on a person to conform to society's 'needs' and 'expectations'. And unlike Arrowsmith, it does not reveal much of the realistic nature of the characters.

Thus, the correct answer is Arrowsmith.