Which solution should a data architect recommend to encrypt existing fields?

Universal Container has implemented Sales Cloud to manage patient and related health records. During a recent security audit of the system it was discovered that same standard and custom fields need to encrypted.

Which solution should a data architect recommend to encrypt existing fields?
A . Use Apex Crypto Class encrypt customer and standard fields.
B . Implement classic encryption to encrypt custom and standard fields.
C . Implement shield platform encryption to encrypt and standard fields
D . Expert data out of Salesforce and encrypt custom and standard fields.

Answer: C