Which is the correct formula for the total cost in the quantity dlscount model?

$(\frac{Q}{2})H+(\frac{D}{Q})S$

$(\frac{Q}{2})H+(\frac{D}{Q})S+PD$

$\sqrt[\frac{2DS}{H}]{s}$

$(\frac{I_{\text{m}\text{a}\text{x}}}{2})H+(\frac{D}{Q})S$