Ummm... The first problem with this question is that the query will not run as written.  The correct answer should be C.  It doesn't matter whether a correctly written query...

Also, your query is returning rows everytime the ID in test = an ID in test.  This will always evaluate to True.  You will get a row back for every...

Since it is a varchar field and not int, you will need to set your fallback value in the coalesce to a varchar value.

coalesce(b.accountNumber, c.accountNumber, d.accountNumber,'No Value') <> 'No Value'

If you needed to do more than just check for existence (like actually retrieve data from the related tables), then you could use the follwoing syntax.  I know it is...