Given the following list of potential authentication credentials, identify as many combinations as possible that can be used to implement (a) a multi-modal authentication process and (b) a multi-factor authentication process. Consider both combinations of two and of three credentials. List of possible credentials:

• Passphrase

• Smartphone that displays text to enter

• Security question

• Voice recognition

• USB flash drive that displays a different code every 60 seconds

• Picture to be identified from a set of pictures