Which of the following statements regarding accounting periods is true?

a$.$ An individual may request IRS approval to change to a fiscal year basis if certain conditions are met.

b$.$ The choice to file on a year$-$end basis must be made with an initial tax return.

c$.$ Almost all individuals file tax returns using a fiscal year basis.

d$.$ Books and records may be kept on a different year$-$end basis than the year$-$end used for tax purposes.