Problem
Your grandpa, who is an economist by training, wants to test your economics knowledge. To accomplish it he offers you the following gift card options for your birthdays and asks you to pick one.
Option I: A $100 gift card for this year's birthday and $100 gift card for the next birthday.
Option II: A $120 gift card for this year's birthday and $80 gift card for the next birthday.
If you can borrow at 100% interest rate but can't lend (effectively making lending interest rate 0%), which option would you choose? Support your decision by drawing your intertemporal budget constraint.