Python Mutable Default Argument
✅ Correct Answer:
B) [10] and [10, 20]
💡 Explanation:
In Python, default arguments are evaluated once at function definition, not every time you call it.
First call → my_list starts as [], appends 10 → [10].
Second call → same list object reused, appends 20 → [10, 20].
This is a classic mutable default argument gotcha in Python.