Which of the following is incorrect?

a. The basis of property acquired in a wash sale is its cost plus the disallowed loss not recognized on the wash sale.

b. Wash sales rules do not apply to gains realized on disposition of securities.

c. If substantially identical shares are purchased within 30 days before or after the date of the loss sale, the transaction is a wash sale.

d. Losses from wash sales are allowed if securities are involved.