Since the pass code it is a 4 code,
The first digit will be : 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, it can be any of the following. So 10 ways to get first number
The second digit will be : 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, it can be any of the following. So 10 ways to get second number
The third digit will be : 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, it can be any of the following. So 10 ways to get third number
The fourth digit will be : 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, it can be any of the following. So 10 ways to get fourth number
So There will be around 104 number of trials to get the right code.
The correct option is (B)