Explanation:

Only statement 1st is incorrect.

Two Dimensional Electron Gas (2DEG)

• It is an electron gas that is free to move in two dimensions, but tightly confined in the third. This tight confinement leads to quantized energy levels for motion in the third direction. Thus the electrons appear to be a 2D sheet embedded in a 3D world. 
• 2DEG is a valuable system for exploring the physics of superconductivity magnetism and their coexistence.
• The need for attaining new functionalities in modern electronic devices has led to the manipulation of property of an electron called spin degree of freedom along with its charge. This has given rise to an altogether new field of spin-electronics or ‘spintronics’.
• The manipulation of electron spin offers new dimensions for basic and applied research, and the potential for new capabilities for electronics technology. This motivates studies of spin polarized electrons in a high mobility two dimensional electron gas (2DEG).
• Spintronics is the study of the intrinsic spin of the electron and its associated magnetic moment, in addition to its fundamental electric charge, in solid-state devices.

Hence option 1st is correct.