Which of the following is true for variable names in Python?

Question: Which of the following is true for variable names in Python?

Options are:

a). unlimited length
b). all private members must have leading and trailing underscores
c). underscore and ampersand are the only two special characters allowed
d). none of the mentioned

correct option is in reply

Also read:

1. All keywords in Python are in?
2. Which of the following is not a keyword in python?
3. Which of the following is an invalid variable in Python?
4. What is the maximum possible length of an identifier?
5. Is Python case sensitive when dealing with identifiers?
6. Why are local variable names beginning with an underscore discouraged?