• Diagnostic Hallmark of Canine IMHA: Spherocytes are the hallmark erythrocyte morphological abnormality pathognomonic for Immune-Mediated Hemolytic Anemia (IMHA) in dogs.
• Mechanism of Spherocyte Formation: When circulating erythrocytes are opsonized with anti-erythrocyte autoantibodies (IgG) and/or complement ($C3b$), splenic and hepatic macrophages partially phagocytose portions of the cell membrane without lysing the whole cell. The damaged RBC reduces its surface-area-to-volume ratio, transforming into a small, rigid, densely staining spherical red blood cell that lacks central pallor.
• Contrasting Erythrocyte Morphologies:
• Acanthocytes: Irregularly spaced, blunt, spurlike projections seen in hemangiosarcoma and liver disorders.
• Schistocytes: Fragmented RBCs formed by mechanical shear stress in DIC.
• Echinocytes: Uniformly scalloped, crenated spikes associated with uremia or artifactual in vitro drying.

Correct option: (4) Spherocytes

• Cardinal Defects of Tetralogy of Fallot:
• Tetralogy of Fallot is a congenital malformation complex of the conotruncal septum consisting of four interrelated structural cardiac defects:
• Ventricular Septal Defect (VSD): Subaortic interventricular communication [TRUE].
• Pulmonary Stenosis: Hypoplastic pulmonary trunk or subpulmonic/infundibular narrowing obstructing right ventricular outflow [TRUE].
• Dextroposition (Overriding) of Aorta: The aortic root is shifted rightward directly above the VSD [TRUE].
• Hypertrophy of Right Ventricle: Secondary compensatory right ventricular myocardial hypertrophy due to systemic pressure overload (Statement B erroneously specifies left ventricular hypertrophy) [Statement B is FALSE].

Correct option: (4) (A), (C) and (D) only.

• Matching Morphological Patterns of Inflammatory Exudates:
• Serous inflammation $\longrightarrow$ (III) Fluid exudate low in protein and cell content: Characterized by transudate-like, clear fluid derived from plasma or mesothelial secretions (e.g., in skin blisters or early burn lesions).
• Fibrinous inflammation $\longrightarrow$ (I) Exudate rich in fibrinogen that polymerizes into fibrin networks: Typical of serous membrane surfaces (pericardium, pleura, peritoneum) showing bread-and-butter gross appearance.
• Purulent (Suppurative) inflammation $\longrightarrow$ (IV) Exudate prominent in neutrophils, liquefactive necrosis, and cellular debris: Typical of pyogenic bacterial infections resulting in pus formation (abscess).
• Catarrhal inflammation $\longrightarrow$ (II) Hypersecretion of mucus from epithelial surfaces: Occurs in mucous membranes of the respiratory and gastrointestinal tracts.
• Conclusion: (A) - (III), (B) - (I), (C) - (IV), (D) - (II) (Option 3).

Correct option: (3) (A) - (III), (B) - (), (C) - (IV), (B) - (I)