Which method would yeild the greatest net result?

[ben_]

An interesting question i stubbled apon today.
All thoughts and comments welcome.

Your bank balance stands at £100.00. You may place up to this amount on one of the following bets. You can stop betting at any time.
You can place a maximum of 20 bets.

The four betting options are as follows:

1)A 100% chance of winning 1.04 times your stake.
2)A 50% chance of winning 2 times your stake.
3)A 33% chance of winning 3 times your stake.
4)A 10% chance of winning 20 times your stake.

So statistically, which is the best route to take to gain the most money?

Cheers