Problem Statement
Which option fully copies a nested list so inner lists are independent?
Explanation
A shallow copy duplicates the outer list but keeps references to the same inner lists. deep copy recursively copies nested structures so edits do not leak back.
Use deepcopy when structures are nested and you truly want independence between old and new.
Code Solution
SolutionRead Only
import copy old=[[1],[2]] new=copy.deepcopy(old) new[0][0]=9 # old unchanged
