Which one of the following rules for selecting a password is the best?

10 digits: 0123456789 26
lower case letters:
26 upper case letters:
33 special characters: `[email protected]#$%^&*()--=+[ ]\{}\;':", ./<>?

a) 8 characters: 4 Numbers, 2 Lowercase Letters, 2 Uppercase letters
b) 7 characters: 4 Numbers, 1 Lowercase Letters, 1 Uppercase letter, 1 Symbol
c) 12 characters: 12 Numbers
d) 9 characters: 4 Numbers, 5 Lowercase Letters

(b) 7 characters: 4 Numbers, 1 Lowercase Letter, 1 Uppercase letter, 1 Symbol

Explanation:

The best rule that makes a password great is that rule that increases the entropy of the password. The entropy of a password is the measure of how easy it is for the password to be cracked e.g by guessing, by brute force cracking, by dictionary attacks and other related cracking methods.

A rule that makes use of a logical combination of the four types of characters - digits, lowercase letters, uppercase letters and special symbols - gives a greater strength to the password than the rules that just make use of the some of the four types of characters.

Increasing the length of the password too is a great way of increasing the entropy of the password. But then, if there is a trade-off between length and combination, the latter is better.

you have to email it to yourself from your phone then download it to either google drive or you computer files. then you can go to where ever you saved it and select it and then copy and paste it. or you could attach it to your question when you are writing it which would be much easier. for example: go to the attachment.