Sam is working as a system administrator in an organization. He captured the principal characteristics of a vulnerability and produced a numerical score to reflect its severity using CVSS v3.0 to properly assess and prioritize the organization's vulnerability management processes. The base score that Sam obtained after performing CVSS rating was 4.0.
What is the CVSS severity level of the vulnerability discovered by Sam in the above scenario?

A. Critical
B. Medium
C. High
D. Low