My highlighter tool is not working. i am unable to select it

[samra5C46]

I am using a Pdf file on my Adobe Reader X. It is not giving me the highlight text option.
plz help 

[try67]

You can only highlight files in this ancient version of Reader if the author enabled that option in advance using Acrobat.

If you upgraded to Acrobat DC you would be able to do it by default on any PDF file, unless it was explicitly forbidden by the author, so the opposite of your current situation.