Answer: C. Service account
Step-by-step explanation:
Service account is one of the special types of account which can be used to grant special privileges to applications and services for the use of the operating system. This is mainly done during catastrophic failures or in some cases of disaster. So in such a case when the system administrator is unable to reach out then special administrator credentials are provided to applications and services for interaction of the operating system through service account.
Option A is incorrect as shared account is used during sharing of the processor in distributed systems.
Option B is incorrect as guest account is used to grant access to the system different guest by hiding the files of user account.
Option D is incorrect as user account is used to grant access to the personnel system of the user.