Solution

The correct answer is /etc/passwd 

Key PointsIn Linux, user passwords are not actually stored in the /etc/passwd file. The /etc/passwd file contains basic information about user accounts, but not the actual passwords. Instead, the password information is typically stored in the /etc/shadow file.

The /etc/shadow file in Linux houses user passwords. When the field is unoccupied, it signifies that password authentication is not required for that user. For heightened security, it is imperative that each user on your system is assigned a password.

So, closest answer is /etc/passwd.