What type of key does this bug leave exposed to the Internet making exploitation of any compromised system very easy?

The Heartbleed bug was discovered in 2014 and is widely referred to under MITRE’s Common Vulnerabilities and Exposures (CVE) as CVE-2014-0160. This bug affects the OpenSSL implementation of the Transport Layer Security (TLS) protocols defined in RFC6520.

What type of key does this bug leave exposed to the Internet making exploitation of any compromised system very easy?
A . Public
B. Private
C. Shared
D. Root

Answer: B