Country Alpha takes $4$ hours to produce a unit of jet fuel and $2$ hours to produce a unit of butter. Country Omega takes $9$ hours to produce a unit of jet fuel and $3$ hours to produce a unit of butter. Based on this, what range of jet fuel for every $60$ units of butter would be mutually beneficial?

Select one:

a$.$ Between $0\mathrm{.}33$ and $0\mathrm{.}5$ units of jet fuel

b$.$ Between $2$ and $3$ units of jet fuel

c$.$ Between $4$ and $9$ units of jet fuel

d$.$ Between $20$ and $30$ units of jet fuel

e$.$ Between $120$ and $180$ units of jet fuel