Calculate the present value of each cashflow using a discount rate of $7\%.$ Which do you prefer the most? Show and explain all supporting calculations!

Cashflow A: receive $$60$ today and then receive $$60$ in four years.

Cashflow B: receive $$12$ every year, forever, starting today.

Cashflow C: pay $$50$ every year for five years, with the first payment being next year, and then subsequently receive $$30$ every year for $20$ years.

Cashflow D: receive $$9$ every other year, forever, with the first payment being next year.