css select dropdown bold on some 's

Question

On a select dropdown, I need to make certain items \'strong/bold\'.

How can I do this?

Example of what I ideally require:

Answer 1

This also works (Firefox 50 and Chrome 55). Items 3 and 5 are shown in bold

   
   
    Kanakangi
    Ratnangi
    Hanumatthodi
    Dhenuka
    Mayamalavagowla
    Chakravaaham