There are two options for the kind of tethering plan you can use. The first, DataPro 4GB for Enterprise, is used by businesses with Enterprise plans with AT&T. This doesn't apply to most users, so unless you get your iPhone through work, you can probably ignore it.
That leaves DataPro 4GB for iPhone, which is what you want. Select that.
The US$45 price refers to the total monthly cost, not the price of tethering alone. Tethering adds $20/month to the $25/month iPhone data plan (it also requires you to drop the unlimited iPhone data plan). Click "next" to continue.
