A. A built-in Python function
B. A one-line anonymous function
C. Lambda is a function in python but user can not use it.
D. None of the above

Solution

B. A one-line anonymous function

Explanation

Lambda functions in Python are concise, anonymous functions often used for short, simple operations. They are defined using the lambda keyword and are particularly useful in situations where a small, temporary function is needed, such as when using functions like map(), filter(), or sorted().