Sauer Milk Incorporated wants to determine the minimum cost of capital point for the firm. Assume it is considering the following financial plans:

Cost $($aftertax$)$ Weights

Plan A

Debt $3\mathrm{.}0\%15\%$

Preferred stock $6\mathrm{.}010$

Common equity $10\mathrm{.}075$

Plan B

Debt $3\mathrm{.}2\%25\%$

Preferred stock $6\mathrm{.}210$

Common equity $11\mathrm{.}065$

Plan C

Debt $4\mathrm{.}0\%35\%$

Preferred stock $6\mathrm{.}710$

Common equity $10\mathrm{.}655$

Plan D

Debt $7\mathrm{.}0\%45\%$

Preferred stock $7\mathrm{.}610$

Common equity $12\mathrm{.}645$

a$-1.$ Compute the weighted average cost for four plans.

Note: Do not round intermediate calculations. Input your answers as a percent rounded to $2$ decimal places.

a$-2.$Which of the four plans has the lowest weighted average cost of capital?

multiple choice

Plan A

Plan B

Plan C

Plan D