Sigma Corp. has a target financing mix of $30\%$ debt and $70\%$ common equity. The before$-$tax cost of Sigma's debt is $10\%.$ Sigma estimates its cost of internal equity at $14\%$ and its cost of new common equity at $17\%.$ Sigma's marginal tax rate is $34\%,$ and it expects to have $$2,100,000$ of profit available for reinvestment in the firm. Sigma's weighted cost of capital is:

a$.14\mathrm{.}28\%$

b$.11\mathrm{.}78\%$

c$.13\mathrm{.}88\%$

d$.12\mathrm{.}38\%$