Look at what the stress strain curve of a low carbon steel actually does near yielding. There is a sharp upper yield point, then the load drops to a lower yield point, and after that the curve runs almost flat for a stretch before strain hardening kicks in. That flat stretch is the yield point elongation, and it is not uniform across the specimen. Instead, narrow bands of concentrated shear deformation start near a stress riser and sweep along the gauge length one after another while the load stays roughly constant. These moving bands are the Lüders bands, and they vanish once the whole gauge length has yielded and uniform hardening begins. Since this is tied to that flat plateau region, the answer is yield point elongation, option (D).