Two interesting things here:
The first is that the BoL page referenced in the explanation has incorrect information on it: it quite clearly says
A computed_column_expression is deterministic when one or more of the following is true:
where actually all need to true, not just one.
The second is that the corrected answer may still be wrong: as someone pointed out in an earlier comment, the BoL page says (twice) that a computed column which is imprecise can be used in an index provided it is persisted. So perhaps item 1 should not be in the list of answers to be checked.
Tom