निम्न में से कौन सा द्वितीयक या गौण आँकड़ों का स्रोत नहीं है?

उत्तर: (C) व्यक्ति द्वारा स्वयं किया गया सर्वे / Survey conducted by the person himself — A survey conducted by oneself is a primary data source (first-hand collection). Secondary data comes from existing sources like magazines, government reports, and internet databases that someone else ...