What keyword is used to define an exception block in Python?

• A. catch
• B. except
• C. finally
• D. handle

Answer: (B)

In Python, the correct keyword used to define an exception block is "except." This keyword is part of the error handling mechanism that allows programmers to manage exceptions that may occur during the execution of a program. When an error occurs, the program flow is interrupted and control is transferred to the exception block defined by the "except" keyword.

Using "except," developers can specify what type of exceptions they want to catch. It enables a more graceful recover from errors rather than allowing the program to crash. For example, when opening a file, if the file does not exist, the program can handle this situation using an "except" block to provide an alternative response, such as displaying an error message.

The other keywords mentioned do have roles in exception handling but are not used specifically to define an exception block. "Catch" is not a keyword in Python; "finally" is used to define a block of code that runs whether an exception occurs or not, and "handle" is not a recognized keyword in Python’s syntax for error handling. Therefore, "except" is the definitive choice for defining an exception block.