The correct answer is: D. permanent provision
A permanent call provision is a call provision that allows the issuer to call the bonds at any time after a certain date, usually after five years. This means that the issuer can force the bondholders to sell their bonds back to the issuer, at a price that is usually set at par value.
A deferred call provision is a call provision that allows the issuer to call the bonds only after a certain date, usually after five years. This means that the issuer cannot call the bonds before that date, even if they want to.
An original provision is a call provision that is included in the bond indenture when the bonds are issued. This means that the call provision was part of the original agreement between the issuer and the bondholders.
A deferred provision is a call provision that is added to the bond indenture after the bonds are issued. This means that the call provision was not part of the original agreement between the issuer and the bondholders, but was added later.
In the case of a bond call provision that is not practiced even after several years of issuance, it is most likely that the provision is a permanent provision. This is because a permanent provision allows the issuer to call the bonds at any time, so there is no reason for the issuer to wait several years before exercising the call provision.