Which one is self-indicator?

Answer: Option B

Potassium permanganate (KMnO₄) is the self-indicator among the following options. The self indicator is the chemical substance that can indicate the presence of the specific substance in the solvent mixture as a colour change at the end of the titration.
Potassium permanganate is a flexible and potent oxidant that can be used by overt or indirect titration to classify many compounds.