Which $A$ gives red colour in the reaction

• Correct answer
  A

  $\mathrm{CH}_3 \mathrm{CH}_2 \mathrm{NO}_2$
• B

  $\left(\mathrm{CH}_3\right)_2-\mathrm{CHNO}_2$
• C

  $\left(\mathrm{CH}_3\right)_3 \mathrm{CNO}_2$
• D

  
  

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