Answer:
C
Explanation:
The reason I would choose C is that the penny doubling each day might seem small but the amount would continue to grow exponentially giving you a might higher payoff than the rest of the options. I don't know the exact amount you would get by it is around 3 mill.
Option B gives you linear growth, which means that by the end of 30 days, you would only have 750,000.
Option A is the worst potion only leaving you with 1 million.