True or False $($Please give a proof or explanation if it is true and give aAccording to the tradeoff theory of capital structure, what is the optimal debt ratio among the choices

under the existence of bankruptcy cost and $40\%$ corporate tax.

a$.0\%$

b$.20\%$

c$.50\%$

d$.$ Does not matter

WACC of a: $14\%$

WACC of b: $12\mathrm{.}6\%$

WACC of c: $13\%$ counterexample if it

is false.$)$

$($a$)$ Each maximum flow defines a unique minimum capacity cut.

$($b$)$ Each minimum capacity cut defines a unique maximum flow.

$($c$)$ If all capacities are odd then there is a maximal flow $v(f)$ such that $f_{ij}$ is odd for all

edges;

$($d$)$ If all capacities are even then there is a maximal flow $v(f)$ such that $f_{ij}$ is even for all

edges.