• Angara Disease (Hydropericardium Syndrome / HPS):
• Etiological Agent: Caused by Fowl Adenovirus serotype 4 (FAdV-4) belonging to species Fowl aviadenovirus C [TRUE].
• Transmission Dynamics: Transmitted both vertically via embryonated eggs and horizontally via the fecal-oral route [TRUE].
• Gross Lesions: Dramatic accumulation of up to $10\text{--}20\text{ ml}$ of clear, straw-colored transudate in the pericardial sac (hydropericardium), alongside a swollen, friable, pale liver and congested kidneys [TRUE].
• Histopathology: Diagnostic presence of large, basophilic intra-nuclear inclusion bodies within degenerating hepatocytes [TRUE].

Correct option: (1) (A), (B), (C) and (D).

• Pathological Hallmark of Anthrax: In ruminants dying of peracute or acute Anthrax (Bacillus anthracis), post-mortem examination reveals colossal splenomegaly (splenic enlargement up to 5–10 times normal size).
• 'Blackberry Jam' Spleen: The splenic capsule is tense and fragile; on incision, the dark, semi-fluid, liquified splenic red pulp oozes out as a soft, unstructured, tarry red-black mass resembling blackberry jam (or currant jelly), accompanied by incomplete rigor mortis, dark unclotted blood oozing from natural orifices, and absence of rigor mortis.
• Safety Caveat: Opening carcasses suspected of anthrax is strictly prohibited to prevent vegetative cells from sporulating upon air exposure.

Correct option: (2) Anthrax

• Mechanism of Fibrinoid Necrosis: Fibrinoid necrosis is a specialized form of tissue death typically involving the walls of blood vessels (vasculitis, malignant hypertension, Arthus reaction, polyarteritis nodosa).
• Depositional Components: Arises when severe immune-complex deposition (Type III hypersensitivity) triggers complement activation and neutrophilic infiltration, disrupting endothelial integrity. Circulating (A) Immunoglobulins, (B) Complement components ($C3$, $C1q$), and (C) Plasma proteins leak into the vessel wall alongside extravasated (D) Fibrin, polymerizing into an amorphous, bright pink, refractile smudgy deposit on H&E staining resembling fibrin.

Correct option: (3) (A), (B), (C) and (D).