Answer:
B Settlement date
Explanation:
The INTERNAL REVENUE SYSTEM under the publication 550: Investment Income and Expenses(including capital gain and losses)
determinates the legal requirement to determinate the cost basis for shares.
When the investor can identify which shares of stock are being sold
the basis is what was paid for the shares plus other cost.
This is important when the investor makes purchases of shares in different time period at different times.
Selling shares with loner than 2-years generates a long-term capital gain while below 2-years are short-term
Also, the cost determinates how much is the gain per share.