Which of the following is the formula to compute present value factor of an annuity of $$1$ according to the internal rate of return method?

a$.$ Present value factor of an annuity of $$1=$ Total present value of net cash flow $$ Amount to be invested

b$.$ Present value factor of an annuity of $$1=$ Total present value of net cash flow $+$ Amount to be invested

C$.$ Present value factor of an annuity of $$1=$ Amount to be invested $+$ Equal annual net cash flows

d$.$ Present value factor of an annuity of $$1=$ Amount to be invested $$ Equal annual net cash flows