The marketable debt securities portfolio of which they are a part is classified as Held to maturity.
Option: C
Explanation:
Debt securities (bonds) classified as held-to-maturity are reported at premium cost or cost benefit policy. Debt securities classified as available-for-sale or held to maturity are reported at fair value.Investments in market where sellers are not intended to sell the thing in the near term should be categorized as available-for-sale.
Unauthenticated gains and losses on available-for-sale securities should be reported as a different component of aggregate income. In international trade cost benefit hypothesis and sale security option more works.