To solve this question, the user needs to have an understanding of digital certificates.
Option A: This option is incorrect. A digital certificate is not a scanned copy of a paper certificate. A digital certificate is an electronic document that verifies the identity of the certificate holder.
Option B: This option is incorrect. Voice signal conversion from analog to digital signal during transmission on a public switched telephone network (PSTN) is not related to digital certificates.
Option C: This option is correct. A digital certificate is an encryption mechanism that confirms the message sender and integrity of the message received. It contains information about the identity of the certificate holder, including their public key.
Option D: This option is incorrect. Option C is the correct statement.