• Biological Species Concept (BSC): Formulated by the evolutionary biologist Ernst Mayr in 1942.
• Definition: Defines a species as groups of actually or potentially interbreeding natural populations that are reproductively isolated from other such groups.
• Key Principle: Species integrity is maintained internally by gene flow via interbreeding among conspecifics, and externally by intrinsic reproductive barriers preventing gene exchange with other species. (Correct answer: Option 3)

• Acclimatization: The gradual physiological adjustment and genetic adaptation of an introduced plant population or cultivar to new climatic and edaphic environmental conditions over successive generations under natural selection.
• Related Terms:
• Domestication: The bringing of wild species under human cultivation and artificial selection.
• Adaptation: An inherent evolutionary morphological or physiological attribute enhancing fitness in a given environment. (Correct answer: Option 2)

• Chronology of Crop Domestication in Agricultural History:
• Barley (Hordeum vulgare) [B]: Domesticated $\approx 10,500\text{ BP}$ (Pre-Pottery Neolithic A/B in the Fertile Crescent).
• Emmer Wheat (Triticum dicoccum) [E]: Domesticated $\approx 10,000\text{ BP}$ in the Near East.
• Asian Rice (Oryza sativa) [A]: Domesticated $\approx 9,000 - 8,000\text{ BP}$ in the Yangtze River basin, China.
• Mung Bean (Vigna radiata) [C]: Domesticated $\approx 4,500\text{ BP}$ in the Indian subcontinent.
• Finger Millet (Eleusine coracana) [D]: Domesticated $\approx 3,000\text{ BP}$ in East Africa and subsequently introduced to India.
• Correct Chronological Sequence: B $\rightarrow$ E $\rightarrow$ A $\rightarrow$ C $\rightarrow$ D (Option 2).

Correct option: (2) B-E-AC-D