Question: According to the PEP 8 coding style guidelines, how should constant values be named in Python?

1. in camel case without using underscores to separate words -- e.g. `maxValue = 255`
2. in lowercase with underscores to separate words -- e.g. `max_value = 255`
3. in all caps with underscores separating words -- e.g. `MAX_VALUE = 255`
4. in mixed case without using underscores to separate words -- e.g. `MaxValue = 255`

Answer: The correct answer of the above question is Option C:in all caps with underscores separating words -- e.g. `MAX_VALUE = 255`