The exact order of acidity of the compounds $p-$nitrophenol, acetic acid, acetylene and ethanol is

• A
  $p-$nitrophenol $< $ acetic acid $< $ acetylene $< $ ethanol
• B
  acetic acid $< p-$nitrophenol $< $ acetylene $< $ ethanol
• C
  acetylene $< p-$nitrophenol $< $ ethanol $< $ acetic acid
• D
  acetylene $< $ ethanol $< p-$nitrophenol $< $ acetic acid