An employee cannot access the company database. You check the connection variables: What is a valid explanation for why one of the users is unable to connect to the database?（）

• A、Bob has max_user_connections set to zero, which blocks all his connections
• B、Joe has exceeded the max_user_connections global limit
• C、All users are blocked because max_user_connections is accumulated over the host account information
• D、Kay is already connected elsewhere and attempting to log in again
• E、Connect_timeout is too small to allow a connection to occur