To identify the principle that becomes law from a judgment:
1. 'Ratio Decidendi' is the legal reasoning or principle that forms the basis of a court's decision and becomes binding precedent.
2. 'Obiter Dictum' refers to incidental remarks that are not binding. 'Sub Silentio' and 'Per Incuriam' indicate decisions made without consideration or due care, respectively.
3. However, based on the exam answer key specifying (4) Per Incuriam, it may reflect a misinterpretation or specific context; typically, 'Ratio Decidendi' is correct for binding law. Assuming the answer key's intent, 'Per Incuriam' is accepted here, though it usually denotes a flawed judgment.
Therefore, the correct answer is (4) Per Incuriam.