How long does an AWS free usage tier EC2 last for?

How long does an AWS free usage tier EC2 last for?
A . Forever
B . 12 Months upon signup
C . 1 Month upon signup
D . 6 Months upon signup

Answer: B

Explanation:

The AWS free usage tier will expire 12 months from the date you sign up. When your free usage expires or if your application use exceeds the free usage tiers, you simply pay the standard, pay-as-you-go service rates.

Reference: http://aws.amazon.com/free/faqs/