A long position in a creditsensitive bond can be synthetically replicated using:

The correct answer is choice 'a'

A long position in a credit sensitive bond is equivalent to earning the risk free rate and the spread on the bond. The risk freerate can be earned through a long position in a treasury bond, and the spread can be earned in the form of premiums on a CDS, which are received by the protection seller, ie the party short a CDS contract. Therefore we can get the same results as a long bond position using a combination of a long treasury bond and a short position in a CDS. Choice 'a' is the correct answer.