A company sells two models of a product$-$Alpha and Omega. If the company sells $10,000$ Alpha models and $2,500$ Omega models, then the sales mix can be

expressed as:

$1$:$2\mathrm{.}5$

$2\mathrm{.}5$:$10$

$10$:$2\mathrm{.}5$

$4$:$1.$