Wheat requires cool weather during its vegetative stages and grain filling. While grain ripening and harvesting typically occur when temperatures begin rising toward $20\text{--}25^\circ\text{C}$, the official examination key designates $14\text{--}15^\circ\text{C}$ as the optimal thermal range for grain maturation and carbohydrate conversion before terminal heat onset. Option analysis: (A) Often represents late harvest ambient temperature. (B) Typical tillering to heading temperature. (C) $14-15^\circ\text{C}$ is designated as the optimal average maturity temperature per official answer key. (D) Chilling temperature during early tillering.

For standard chickpea (Cicer arietinum) cultivation under irrigated and rainfed conditions, the recommended spacing is $30\text{--}45\text{ cm}$ between rows and $10\text{--}15\text{ cm}$ between plants ($30\text{ cm} \times 10\text{ cm}$ for desi types, and $45\text{ cm} \times 15\text{ cm}$ for spreading and bold-seeded kabuli types). Option analysis: (A) Spacing is suited for red gram (pigeonpea). (B) Plant-to-plant distance is too dense. (C) Plant spacing is too narrow. (D) 30-45 and 10-15 is the standard agronomic recommendation.

Sprinkler irrigation applies water overhead in the form of artificial rain and is ideal for: (A) Highly permeable sandy soils where surface irrigation would cause excessive deep percolation losses; (B) Undulating rolling terrain where land leveling is expensive or exposes infertile subsoil; and (D) Close-growing field crops (wheat, pulses, oilseeds, alfalfa). High wind speeds ($\gt 10\text{--}15\text{ km/h}$) distort droplet distribution patterns, causing poor uniformity and excessive evaporation losses, making sprinklers unsuitable. Option analysis: (A) High wind speed (C) is unsuitable. (B) (A), (B) and (D) only correctly identifies suitable conditions. (C) Includes high wind. (D) Omits sandy soils.

According to the Directorate of Economics and Statistics (DES), Ministry of Agriculture & Farmers Welfare final estimates for 2020-21, the state rankings in total foodgrain production were: 1. Uttar Pradesh ($56.08\text{ million tonnes}$, $\sim 18.06\%$); 2. Madhya Pradesh ($34.80\text{ million tonnes}$, $\sim 11.20\%$); 3. Punjab ($30.13\text{ million tonnes}$, $\sim 9.70\%$); 4. Rajasthan ($24.81\text{ million tonnes}$, $\sim 7.99\%$). Thus, the correct descending order is (B), (D), (A), (C). Option analysis: (A) Punjab is 3rd, not 1st. (B) Uttar Pradesh is the top producer. (C) Inverts MP and Punjab. (D) (B), (D), (A), (C) is the correct sequence.