To solve this problem, we need to understand the properties of ortho and para-nitrophenols.$\\$• Ortho-nitrophenol and para-nitrophenol are isomers, meaning they have the same molecular formula but different structures.$\\$• The key difference between these isomers is their boiling points due to their ability to form intermolecular hydrogen bonds.$\\$• Ortho-nitrophenol can form intramolecular hydrogen bonds, which reduces its ability to form intermolecular hydrogen bonds.$\\$• Para-nitrophenol, on the other hand, forms strong intermolecular hydrogen bonds.$\\$• As a result, ortho-nitrophenol has a lower boiling point compared to para-nitrophenol.$\\$Given these properties, steam distillation is the most suitable method for separating these isomers.$\\$• Steam distillation is effective for separating compounds with different boiling points, especially when one of the components is steam volatile.$\\$• In this case, ortho-nitrophenol is steam volatile due to its lower boiling point, while para-nitrophenol is not.$\\$Therefore, steam distillation can be used to separate ortho-nitrophenol from para-nitrophenol.$\\$Thus, the correct option is Option 3: Steam distillation.