Answer :
Realized gains and losses on investment securities calculated (D). Both a and b
Explanation:
Realized gain/loss is the Total amount of gain and loss realized from the sale of securities.
A realized loss refers to the monetary value of a loss that is the outcome of a trade.
A realized gain is defined as the excessive cost obtained after the deduction of the cost and the prior unrealized losses(or adjusted cost basis) over the proceeds from the sale.
An Unrealized gain can be defined as an increase in the value of the investment which is the outcome of an increase in the market value
Thus we can say that Realized gains and losses on investment securities calculated (D). Both a and b