What is the prerequisite for a costumer to enable Docusign as their signature tool?

What is the prerequisite for a costumer to enable Docusign as their signature tool?
A . The docusign application is enabled on the costumers mobile devices
B . The costumers existing docusign account can be used for onboarding only
C . An embedded signature is enabled
D . The costumer needs a docusign account

Answer: D