Final answer:
The Lexington Triad consists of Alpha Tau Omega, Kappa Alpha Order, and Sigma Nu, all of which were founded at Washington and Lee University in Lexington, Virginia.
Step-by-step explanation:
The Lexington Triad refers to a trio of fraternities that were all founded at Washington and Lee University in Lexington, Virginia. These fraternities are Alpha Tau Omega (ATO), Kappa Alpha Order (KA), and Sigma Nu. These three fraternities have become notable within the Greek life community and each has rich histories and distinct memberships since their respective foundings between the years of 1865 and 1869.