Choice "B" is correct. All perfected security interests are paid first. Since the security interest here was filed more than 90 days before the bankruptcy, this event does not constitute a voidable preference.
Choice "d" is incorrect. The creditor is either an involuntary case gap creditor (third priority) or a creditor with a disallowed post-petition claim; the facts are unclear. In either case, a secured creditor would have priority.Choice "c" is incorrect. Wage claims for wages earned within 180 days of the bankruptcy have a fourth priority. Older wage claims are treated as general unsecured claims and are paid last. In either case, the wage claims are subordinate to a perfected security interest.
Choice "a" is incorrect. If the federal government obtains a lien for taxes against the debtor's estate before the bankruptcy petition is filed, the federal tax lien is treated as a secured interest. However, this interest is subordinate to the March 20 secured claim because the March 20 interest was perfected before the tax lien attached.