• Target Organism for Milk Thermal Processing:
• Historically, milk pasteurization parameters were established to kill Mycobacterium bovis and Mycobacterium tuberculosis.
• However, research demonstrated that Coxiella burnetii (the obligate intracellular bacterium causing Q-fever, a dangerous zoonosis) is the most heat-resistant vegetative pathogen found in raw milk.
• Consequently, modern international HTST pasteurization standards ($72^\circ\text{C}$ for 15 seconds) were elevated specifically to ensure the guaranteed thermal destruction of Coxiella burnetii.
• nalysis:
• (Coxiella burnetii): Correct.

Correct option: (3) Coxiella burnetii