Answer : 4. "संप्रभु, समाजवादी, धर्मनिरपेक्ष, लोकतांत्रिक गणराज्य"
Explanation :

Preamble to the Constitution of India is a brief intraductory statement that sets out the guiding purpose and principles of the documents and indicates the source from which the document derives its authority meaning, the people.