Which of the following is not a valid password?

The password "Appl3Pie" is not invalid; it actually incorporates a mix of uppercase letters, lowercase letters, numbers, and is of a reasonable length, making it a strong candidate for a valid password. The presence of "3" as a substitute for the letter "e" adds complexity, which is beneficial for password strength.

In the context of password creation, valid passwords often combine characters in a way that enhances security. The other options also follow similar principles of security by mixing different character types and maintaining a good length, which is why they are considered valid passwords. Therefore, "Appl3Pie" does meet the necessary criteria and is in fact valid. The correct analysis suggests that all given options are acceptable as passwords, contrary to the answer choice provided.