If $2$ $\text{cm}$ represents $6000\text{km}$, $1\text{cm}$ represents $3000\text{km}$, and $0.1\text{cm}$ represents $300\text{km}$. 
On a map of the Andes, if $2$ $\text{cm}$ represents $6000$ $\text{km}$, then  ~represents $300$ $\text{km}$ . 

  $$0.1$$ 
  $$0.5$$ 
  $$10$$ 
  $$20$$ 