The correct answers are C and D. PEP 8 recommends that module names should be short and entirely lower-case; underscores may be used only when they improve readability. This keeps imports clean and predictable. PEP 8 also warns against using the single-character variable names l, O, or I because they can be visually confused with 1 and 0 in many fonts. Option A is incorrect because Python class names should normally use the CapWords convention, not mixedCase. Option B is incorrect because exception names are class names and should follow class naming conventions; if the exception represents an error, the name should usually end with Error.