Which method of password cracking takes the most time and effort?

A.
Brute force

B.
Rainbow tables

C.
Dictionary attack

D.
Shoulder surfing

Explanation:
Brute-force cracking, in which a computer tries every possible key or password until it succeeds, is typically very
time consuming. More common methods of password cracking, such as dictionary attacks, pattern checking,
word list substitution, etc. attempt to reduce the number of trials required and will usually be attempted before
brute force.
https://en.wikipedia.org/wiki/Password_cracking