Consider sunlight incident on a slit of width \(10^{4}~\mathring{A}.\) The image seen through the slit shall:
1. be a fine sharp slit white in colour at the centre
2. a bright slit white at the centre diffusing to zero intensities at the edges
3. a bright slit white at the centre diffusing to regions of different colours
4. only be a diffused slit white in colour