In Python, indentation determines which statements belong to an if block.
Example:
temperature = 30
if temperature > 25:
print( " It is warm. " )
print( " Drink water. " )
Both print() statements are executed when the condition is true because they share the same indentation level under the if statement.
Python does not use parentheses, semicolons, or square brackets to define the body of an if statement. It uses indentation.
Therefore, the correct answer isB. Lines that share the same indentation level.

See the Step by Step Solution below in Explanation.
Explanation:
Step 1: The expression number % 2 == 0 checks whether the number is even.
Step 2: The original code writes True and False, but it does not return them.
Step 3: A function must use the return statement to send a value back to the caller.
Correct code:
def is_even(number):
if number % 2 == 0:
return True
else:
return False
Simplified correct code:
def is_even(number):
return number % 2 == 0
Example:
print(is_even(4))
print(is_even(7))
Output:
True
False

When Python code is written in a text editor, the developer should save the file, usually with a .py extension, and run it using the Python interpreter.
Example terminal command:
python script.py
Python's documentation explains that a Python module is a file containing Python definitions and statements, usually saved with the .py suffix.
Therefore, the correct answer isA. Save the file and use a Python interpreter.