विधान (a) : म.अ. जिन्हा यांनी काँग्रेस सोडली.
कारण (b) : त्यांना काँग्रेस मधील गबाळ्या कपड्यांतील हिंदुस्तानी बोलणारे सदस्य आवडले नव्हते.
पर्यायी उत्तरे :

The correct answer is Option A (Both (a) and (b) are true and (b) is the correct explanation for (a).).

Key Points:
• M.A. Jinnah's Exit from the Indian National Congress (Nagpur Session 1920):
• Exit from Congress (Assertion a): Muhammad Ali Jinnah, who began his career as an apostle of Hindu-Muslim unity and a constitutional moderate, resigned from the Congress at the Nagpur session in December 1920.
• Sociological and Stylistic Clashes (Reason b): Historians (including Bipan Chandra and Ramachandra Guha) note that Jinnah—an elite, Westernized, English-speaking constitutionalist who wore immaculate Savile Row three-piece suits—was completely alienated by the sudden Gandhian mass populist wave. Jinnah deeply disliked the mass emotionalism, religious overtones of Khilafat, and the influx of rustic, khadi-clad, 'ill-dressed' Hindustani-speaking masses who took over Congress deliberations and shouted down constitutional legalism.
• Hence, according to standard historiography and MPSC official key, both (a) and (b) are true and (b) provides the correct contextual explanation for (a) (Option 1).
• Key Takeaway: Jinnah left Congress in 1920, alienated by Gandhian mass agitation, khadi culture, and the influx of Hindustani-speaking rural cadres.