In a triangle ABC, if $\mathrm{r}_1: \mathrm{r}_2=3: 4$ and $\mathrm{r}_2: \mathrm{r}_3=2: 3$, then $\mathrm{a}: \mathrm{b}: \mathrm{c}=$

• A

  $2: 3: 4$
• B

  $3: 4: 5$
• C

  $4: 5: 6$
• Correct answer
  D

  $5: 6: 7$

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