Read the following statements carefully:
1. Scientists have successfully developed the world's first 4D printing for quartz, that can be used to create complex, shape-changing objects.
2. 4D printing is conventional 3D printing combined with the additional element of time as the fourth dimension.
3. The printed objects can re-shape or self-assemble themselves over time with external stimuli, such as mechanical force, temperature.
Which of the above statements is/are correct?