How do you enforce Object and Field-Level Security (FLS) in SOQL using WITH USER_MODE, WITH SYSTEM_MODE, or WITH SECURITY_ENFORCED?

Apex runs in system mode by default, so enforce user permissions explicitly:

• WITH USER_MODE: enforces the user's object permissions, FLS and sharing rules; errors if inaccessible fields are queried.
• WITH SYSTEM_MODE: explicitly run in system mode (ignores FLS/CRUD; sharing follows class declaration).
• WITH SECURITY_ENFORCED: older; checks object and field access of fields in SELECT, throws exception.

List<Account> accs = [SELECT Id, Name FROM Account WITH USER_MODE];

Prefer USER_MODE, which also enforces filters and works with DML (Database.insert(records, AccessLevel.USER_MODE)).