Company X pays interest to the amount of R$1500$ a year on total liabilities of R$10000.$ It can also issue bonds with a YTM of $12\%.$ What will the relevant before tax cost of debt be when calculating that WACC for the company?

a$.$

$15\%$

b$.$

$8\%$

c$.$

$18\%$

d$.$

$12\%$