Use of Pen or Pencil depends on the rules set by the OMR exam body and follow the following rules for filling the OMR sheet.
Fill the OMR circle completely. Avoid partial filling of circle..
First mark the OMR circles/boxes in the test answer sheet slightly and then darken the filled circles/boxes.
Completely darken the respective circle for your response.
As instructed in OMR test use blue or black point pen to fill the OMR answer sheet.
Instructions are also provided to use specific blue or black pen. Then use that specific pen.
Use a gel pen only in case you don’t have a ball pen. Make sure your marks are drying well.
Don't use a gel pen on two sided sheets.
The use of ink pen or marker pen or sketch pen which can bloat or spill is strictly prohibited.
Sometimes candidates apply too much ink by repeatedly circling the already darkened bubble this might create blotting or a hole in the answer sheet. Avoid this.
Don't use a pencil other than HB or darker 2B pencil.
Sometimes candidates do not pay attention to the pencil they are buying and bring in just any pencil. Check the pencil you have purchased for darkness. If it is not dark enough, consider another brand. It is better to buy HB pencils of 2-3 brands and check them for darkness first and use the darker one.