• Bancroft's Rule of Emulsion Formulation:
• Theoretical Axiom:
• 'The phase in which an emulsifier is preferentially soluble constitutes the continuous (external) phase of the emulsion.'
• Application:
• If a surfactant has low Hydrophile-Lipophile Balance (HLB $3 - 6$) and is soluble in the oil phase, it stabilizes Water-in-Oil (W/O) emulsions (e.g., butter, margarine).
• Hydrophilic surfactants (HLB $8 - 18$) soluble in water form Oil-in-Water (O/W) emulsions (e.g., milk, mayonnaise).
• Conclusion: Water-in-oil emulsions (Option 2).

Correct option: (2) Water-in-oil emulsions