The best answer is B
i The chart of accounts refers to the accounting system, the code of
accounts to the WBS. Whilst these should be linked, they are not the
same.
ii Links between the WBS and the activities in the schedule are
required; however, this information is usually in a code field or a text
field, not the Task ID. There are likely to be several activities to each
WBS element and the WBS code of accounts is a fixed structure.
Task IDs can change.