The original issue discount (OID) is a term used in the bond market to represent the difference between the face value of a bond and its original issue price. In the context of zero-coupon bonds, which do not pay periodic interest, the OID essentially represents the total return an investor will receive upon the bond's maturity. In this scenario, the bond was originally issued at a price of $690, and it carries a face value of $1000. Therefore, the OID is the difference between the face value and the original issue price, which is $1000 - $690 = $310. This amount represents the total return that the original bondholder will receive if they hold the bond until maturity.

Choice B is incorrect. The original issue discount (OID) is not the difference between the purchase price of $690 and the price at which Muhammad Zubair bought it ($855). The OID is determined at the time of initial issuance, not when it was purchased by Zubair.

Choice C is incorrect. The original issue discount (OID) cannot be calculated as the difference between Zubair's purchase price ($855) and face value ($1000). Again, OID refers to the discount at which a bond was originally issued, not its subsequent purchase prices.

Choice D is incorrect. The original issue discount (OID) does not involve any current amortized value in its calculation. It solely depends on the initial issuance price and face value of a bond.