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

(a) Vera starts trading on 1 January 2019, preparing accounts annually to 31 December.

(b) Wilbur starts trading on 1 October 2019. He chooses 30 June as his annual accounting date and prepares his first accounts for the nine months to 30 June 2020.

(c) Yasmin starts trading on 1 February 2019. Her annual accounting date is 30 April and she prepares her first accounts for the 15 months to 30 April 2020.