What does the term "arsenal of democracy" refer to? What is the significance of the team when looking at the ending the Great Depression in the U. S.?

In this quote british secretary of state william pitt is urging connecticut toa) hold the front from invading native tribes. b) raise troops and fight the french in canada. c) support the french in their efforts to hold on to canada. d) reject war with the french in hopes of ending the conflict.