Assurance provided by a review is substantially less than an audit. Which of the following statements is true regarding these services?

Assurance provided by a review is substantially less than an audit. Which of the following statements is true regarding these services?

a. A review requires more substantive evidence than an audit.
b. An audit requires less evidence related to internal control than a review.
c. A review requires less evidence than an audit.
d. None of the above statements is true.