As a winner of a local competition, you can choose one of the following prizes:

(a) $100,000 now

(b) $170,000 at the end of 4 years

(c) $11,600 a year forever starting from next year

(d) $6,000 next year and increasing thereafter by 5% a year forever

(e) $18,000 per year starting next year for 10 years

(f) $20,000 next year, increasing thereafter by 3% a year and stopping after the 7th payment

If the interest rate is 12%, which prize is the most valuable?