The Brahmaputra, Irrawady and Mekong rivers originate in Tibet and flow through narrow and parallel mountain ranges in their upper reaches: Of these rivers, Brahmaputra makes a "U" turn in its course to flow into India. This "U" turn is due to?

• A. Uplift of folded Himalayan series
• B. Syntaxial bending of geologically young Himalayas
• C. Geo-tectonic disturbance in the tertiary folded mountain chains
• D. Both (a) and (b) above