The Magic Money Fairy is here to bless you, which power are you taking for life?

You're one of the lucky few to randomly gain the Magic Money Fairy's favor, and she offers you one of the following blessings:

1. Price Lock: You become immune to inflation. Whatever price everything is at the time you receive the blessing, it remains that way for you until you die.
2. Double Discounts: Whatever the discount is, you get double it up to the item or service being free. You do not receive extra cash if the doubled discount exceeds 100%.
3. Super Saver: Any money you manage to save from any sources of income will magically double 30 days after it was earned. This can only happen once per each newly earned dollar, so money saved from previous paychecks or investment income cannot keep doubling every 30 days.
4. Risk-free Investing: You can never lose money on an investment. No matter what the actual market value is, you will always be able to cash out at the price you bought in. If the investment appreciates in value, you can profit as normal.
5. Interest Amplifier: You earn twice the rate of interest on any account in your name. If your country's tax authority would classify it as interest income, you get double the rate. If you have any debt, this power instead halves the interest rate you would be charged on the debt.

Which one are you picking?