Popcorn Hack #1

Fingerprint - because it is something that is unique to you and only you.

Popcorn Hack #2

D & A - Because there are multiple steps to successfully authenticating. For D, you need to only have a username and for A a password and username is only required to sign in.

Popcorn Hack #3

B - The same key is used both for encryption and decryption, so the answer is B. Some other answer choices are not examples of encryption.

Popcorn Hack #4

A good password is a password that contains numbers, letters, decent length, and special characters.