A massless string and a spring connect two blocks A and B to each other. Block B slides over a frictionless inclined plane while block A slides over horizontal surface. Coefficient of friction between block A horizontal surface is $\mathrm{\mu }=\mathrm{0.2.}$At the instant shown blocks are moving with constant speed. Mass of block A and energy stored in spring are respectively. $\left[g=10\text{m}/{\text{s}}^2,{\text{m}}_{\text{B}}=2\text{kg}\right]$

• A

  $5\mathrm{ }\mathrm{k}\mathrm{g},\mathrm{ }1\mathrm{J}$
• B

  $10\mathrm{ }\mathrm{k}\mathrm{g},\mathrm{ }0.05\mathrm{ }\mathrm{J}$
• Correct answer
  C

  $5\mathrm{ }\mathrm{k}\mathrm{g},\mathrm{ }0.05\mathrm{ }\mathrm{J}$
• D

  $10\mathrm{ }\mathrm{k}\mathrm{g},\mathrm{ }1\mathrm{J}$

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