Identify basis periods for the first three tax years in each of the following situations:

(a) Vera started trading on 1 January 2021, preparing accounts annually to 31 December.

(b) Wilbur started trading on 1 October 2020. He chose 30 June as his annual accounting date and prepared his first accounts for the nine months to 30 June 2021.

(c) Yasmin started trading on 1 February 2021. Her annual accounting date is 30 April and she prepared her first accounts for the 15 months to 30 April 2022.