Read the following stages about the preparation of a permanent slide of onion cell.

1)    Place the peel on the slide, make sure that it is not folded and covered with cover slip

2)    Break the onion piece and separate middle thin layer

3)    Put a drop of water on the slide and keep onion layer on the slide.

4)    Put safranin or methylene blue stain on the layer.

 

Find the correct order of stages.