Final answer:
The error in the given line of code is that a variable name is included within the parenthesis of the string being printed.
Step-by-step explanation:
The correct answer is option 3) A variable name is included within the parenthesis of the string.
In the given line of code, "x" is a variable name, and it is included within the parenthesis of the string being printed. This would cause an error because a variable cannot be directly included within a string without formatting or concatenation. To fix this, the variable should be concatenated with the string using the '+' operator, like this:
x = 4
print(str(x) + ' is the value of x')