How was Tjalling Koopmans awarded the Noble Prize in Economics?

Name: Tjalling Koopmans.
Real Name: Tjalling Charles Koopmans.
Country: Netherlands, United States.
Date of Birth: 28 August 1910.
Died: 26 February 1985.
Education: Graduation from University of Utrecht, and Ph.D. from University of Leiden.
Subjects Of Study: Linear programming econometrics.
Popularly Known: Transport economics, Hitchcock–Koopmans transportation problem, Ramsey–Cass–Koopmans model, and Koopmans’ theorem.
Noble Prize Year: Nobel Prize for Peace in 1975, for their contributions to the theory of the optimum allocation of resources.