Concept:
The Principle of Minimum Potential Energy states that among all kinematically admissible displacement fields satisfying the boundary conditions, the actual displacement field minimizes the total potential energy of the system.
The minimization of the total potential energy leads to the compatibility of deformations in a linear elastic structural system.
Step 1: State the principle of minimum potential energy.
The total potential energy of a structure is
\[
\Pi = U-W,
\]
where
\[
U=\text{Strain energy},
\]
and
\[
W=\text{Work done by external forces}.
\]
For equilibrium,
\[
\delta\Pi=0,
\]
and for stable equilibrium,
\[
\delta^2\Pi>0.
\]
Step 2: Interpret the result.
The displacement field that minimizes the total potential energy satisfies the compatibility requirements of deformation.
Thus, minimization of potential energy yields the compatibility conditions.
Hence,
\[
\boxed{\text{Minimization of potential energy yields compatibility conditions.}}
\]
Therefore, the correct option is
\[
\boxed{(A)\;\text{Compatibility conditions}.}
\]