X$-$Tra Ltd$.$ Has a firm$-$wide WACC of $10\%.$ However, it uses a project's unique risk and WACC in its capital budgeting decisions. This decision making approach is called

a$.$ the discounted cash flow approach.

b$.$ the systematic risk approach.

c$.$ the subjective approach.

d$.$ the net present value approach.

e$.$ the pure play approach.