The Markownikoff  rule is best applicable to the reaction between 

Markownikoff's rule states that addition of halides to unsymmetrical alkenes takes place in such a manner that the negative part of the adduct attaches itself to that carbon atom which contains lesser number of hydrogen atoms. 

Here ${\mathrm{C}}_3{\mathrm{H}}_6\left\{{\mathrm{CH}}_3-\mathrm{CH}={\mathrm{CH}}_2\right\}$  is an unsymmetrical alkene and the reagent is HBr, hence Markownikoffs rule is best applicable for this reaction.