The series combination of two batteries, both of the same emf $10 \mathrm{\;V},$ but different internal resistance of $20\; \Omega$ and $5\; \Omega,$ is connected to the parallel combination of two resistors $30\; \Omega$ and $\mathrm{R}\; \Omega .$ The voltage difference across the battery of internal resistance $20\; \Omega$ is zero, the value of $\mathrm{R}(\text { in } \Omega)$ is 
  • A$30$
  • B$26$
  • C$36$
  • D$15$
JEE MAIN 2020, Diffcult
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