Detailed Answer
(a) A change in accounting principle is a change from
one generally accepted principle to another generally accepted
principle. A correction of an error is the correction of a mathematical
mistake, a mistake in the application of an accounting
principle, an oversight or misuse of existing facts, or a change
from an unacceptable principle to a generally accepted one.
Therefore, a switch from the cash basis (unacceptable) to the
accrual basis (acceptable) is a correction of an error reported as a
prior period adjustment.