Which of the following was a new military technology used in World War I? Select all that apply.

A. machine guns

B. submarines

C. cannons

D. rifles

I would say submarines because machine guns were used against Louis Riel or a similar gun the Gatling gun in 1885, and of course cannons were used in the large sailing ships of the 1500's and the rifle of course had been around for a long time at least back to the 1500's too.

The answer is A. machine guns