A nice attire like what you see in the picture is the required attire for the board exams. According to Professional Regulations Commission (PRC) The required attire for female is school uniform or white blouse or T-shirt and for male, school uniform or white polo shirt or T-shirt.
Dressing up accordingly is one important factor in the board exams. Knowing that you abide with the rules will give you peace of mind that you will be accepted in the examination area.
It will also give you the feel of the board exam itself and this may give you the energy to give your best. So, dress up and get ready for the board exams.