The alkane that can be oxidized to the corresponding alcohol by $\mathrm{KMnO}_4$ as per the equation
is, when:

• A

  $\mathrm{R}_1=\mathrm{H} ; \mathrm{R}_2=\mathrm{H} ; \mathrm{R}_3=\mathrm{H}$
• Correct answer
  B

  $\mathrm{R}_1=\mathrm{CH}_3 ; \mathrm{R}_2=\mathrm{CH}_3 ; \mathrm{R}_3=\mathrm{CH}_3$
• C

  $\mathrm{R}_1=\mathrm{CH}_3 ; \mathrm{R} 2=\mathrm{H} ; \mathrm{R}_3=\mathrm{H}$
• D

  $\mathrm{R}_1=\mathrm{CH}_3 ; \mathrm{R}_2=\mathrm{CH}_3 ; \mathrm{R}_3=\mathrm{H}$

Solution

Generally alkanes resist oxidation but alkane with tertiary H atom(s) can be oxidised to corresponding alcohols by $\mathrm{KMnO}_4$
$\therefore \mathrm{R}_1 \Rightarrow \mathrm{CH}_3 \quad \mathrm{R}_2 \Rightarrow \mathrm{CH}_3 \quad \mathrm{R}_3 \Rightarrow \mathrm{CH}_3$

Hence, the correct answer is option: 'B'.