The strength of a salt solution is $p\%$ if $100$ ml of the solution contains $p$ grams of salt. If three salt solutions $\text{A, B, C}$ are mixed in the proportion $1:2:3$, then the resulting solution has strength $20\%$. If instead the proportion is $3:2:1$, then the resulting solution has strength $30\%$. A fourth solution, $\text{D}$, is produced by mixing $\text{B}$ and $\text{C}$ in the ratio $2:7$. The ratio of the strength of $\text{D}$ to that of $\text{A}$ is
- $2:5$
- $1:3$
- $1:4$
- $3:10$