The clinical presentation described in the question fits into the category of "Unstable Angina." Key points for this diagnosis are:

• Acute onset chest pain.
• ECG changes showing ST depression and T wave inversion.
• Normal cardiac biomarkers, indicating no myocardial necrosis.

In cases of Unstable Angina, the goal is to stabilize the patient's condition and prevent progression to myocardial infarction. This typically involves:

1. Antiplatelet Therapy: Aspirin is usually the first-line treatment, often combined with another antiplatelet agent such as Ticagrelor or Clopidogrel to reduce the risk of thrombus formation.

2. Anticoagulation: Low Molecular Weight Heparin (LMWH) is commonly used subcutaneously to stabilize the patient and prevent further coronary artery thrombosis.

The correct management in this scenario is Antiplatelets + LMW Heparin subcutaneous, as these directly address the prevention of thrombosis and stabilization of the coronary artery, which is crucial in unstable angina.

Here's a breakdown of why the other options are not suitable:

• Oxygen + Aspirin + Ticagrelor + Metoprolol: While uses some appropriate elements, Metoprolol (a beta-blocker) is not a first-line treatment in acute unstable angina without further evaluation of heart function.
• Oxygen + Sublingual nitroglycerin + Antiplatelets + Streptokinase: Streptokinase is a thrombolytic agent used in acute myocardial infarction with ST elevation for clot dissolution, which is not indicated here.
• Oxygen + Sublingual nitroglycerin + Digoxin: Digoxin is primarily used for heart rate control in atrial fibrillation and has no role in acute management of unstable angina.

Hence, the best answer is Antiplatelets + LMW Heparin subcutaneous.