Professional skepticism means being alert. Which of the following is/are included?

(I) Audit evidence that contradicts other audit evidence obtained. (II) Information that brings into question the reliability of documents & responses to inquiries to be used as audit evidence. (III) Conditions that may indicate possible fraud. (IV) Circumstances that suggest the need for audit procedures in addition to those required by the PSAs.

a. I and II only b. All of the above c. II and IV only d. III and IV only