Which of the following statements about an accrual is true?

a$.$ It is normally the result of cash being received or paid before the revenue is earned or the expense is incurred.

b$.$ It is initially recorded as a liability but become revenue over time.

c$.$ It is normally the result of cash being received or paid after revenue has been earned or an expense has been incurred.

d$.$ It is initially recorded as an asset but becomes an expense over time.