The sharp melting point of crystalline solids is due to ________

Question

$\begin{array}{1 1}(a)\text{a regular arrangement of constituent particles observed over a short distance in the crystal lattice} \\(b)\;\text{a regular arrangement of constituent particles observed over a long distance in the crystal lattice}\\(c)\text{same arrangement of constituent particles in different direction } \\(d) \text{different arrangement of constituent particles in different directions } \end{array}$