Solution:

This is a logic question and can be answered if
one realizes
that the TRUTH of a LIE is a LIE, and the LIE of a TRUTH is a LIE. You need one guard to give you the *other*
guard’s answer. Knowing this one
could ask a question like, “If I were to
ask the other guard which door leads to freedom, what would he say?”

If you ask the guard who always tells the truth, he would
tell you the other guard would point you to the door of death. If you ask the guard who always lies, he
would tell you the opposite door of the truth-telling guard and point
you to
the door of death. In either case, both
guards will point to the door of death so you should choose the other
one.