Final answer:
In MySQL, the SQL mode that changes syntax and behavior to conform more closely to standard SQL is ANSI_QUOTES. This mode requires using double quotes for string identifiers, aligning with the ANSI SQL standard. Other modes like STRICT_TRANS_TABLES, IGNORE_SPACE, and TRADITIONAL have different functionalities.
Step-by-step explanation:
The MySQL server can operate in different SQL modes which alter how the database interprets SQL syntax and enforces data validation rules. The mode that changes syntax and behavior to conform more closely to standard SQL is b) ANSI_QUOTES. When ANSI_QUOTES is enabled, it allows only double quotes as string identifiers, which is in compliance with the ANSI SQL standard. This differs from the default mode, where MySQL interprets single and double quotes as string literals and identifiers such as table or column names must be enclosed in backticks (`).
It's important to note that other modes mentioned, like STRICT_TRANS_TABLES, IGNORE_SPACE, and TRADITIONAL, have different roles. STRICT_TRANS_TABLES enforces strict data validation rules for transactional tables to prevent invalid data from being inserted. IGNORE_SPACE allows spaces between a function name and the parenthesis following it, which is not normally permitted in standard SQL. TRADITIONAL mode makes MySQL behave more like traditional SQL servers by enforcing strict data validation.