भारतासारख्या विकसनशील देशात राष्ट्रीय उत्पन्न मोजण्यात खालीलपैकी कोणत्या अडचणी आहेत ?
a. असंघटीत आणि विखुरलेले उत्पादन
b. निर्वाह शेती
c. पुरेशा सांख्यिकीय आकडेवारीची उपलब्धता
d. निरक्षरता

The correct answer is Option B (a, b and d).

Key Points:
• National Income Accounting Challenges: Developing nations like India face specific structural and statistical hurdles when computing National Income (GDP/GNP).
• Subsistence Farming (b): A large portion of agriculture in India is for self-consumption (subsistence). Since these goods never enter the formal market, estimating their monetary value is highly difficult, leading to underestimation of National Income.
• Unorganized Sector (a): A vast majority of the Indian workforce operates in the informal/unorganized sector (e.g., street vendors, small artisans). Their scattered and undocumented production makes data collection extremely challenging.
• Illiteracy (d): Due to high levels of illiteracy, many small-scale producers and traders do not maintain proper accounting books, making direct income assessment nearly impossible.
• The Trap in Option (c): The statement says "Availability of adequate statistical data". The availability of data is a *solution* or a positive trait, not a difficulty. The actual difficulty is the LACK or NON-AVAILABILITY of adequate statistical data. Because of this phrasing, option 'c' is excluded.
• Conclusion: Therefore, the correct difficulties mentioned are a, b, and d.
• Key Takeaway: Read carefully: 'Availability of data' is not a difficulty, the 'Lack of data' is. Hence, a, b, and d are the correct challenges.