After creating a new lAM user which of the following must be done before they can successfully make API calls?

After creating a new lAM user which of the following must be done before they can successfully make API calls?
A . Add a password to the user.
B . Enable Multi-Factor Authentication for the user.
C . Assign a Password Policy to the user.
D . Create a set of Access Keys for the user.

Answer: D

Explanation:

Reference: http://docs.aws.amazon.com/IAM/Iatest/UserGuide/Using_SettingUpUser.htmI