Which configuration file and stanza pair will mask possible SSNs in the log events?

Social Security Numbers (PII) data is found in log events, which is against company policy. SSN format is as follows: 123-44-5678.

Which configuration file and stanza pair will mask possible SSNs in the log events?
A . props.conf [mask-SSN]
REX = (?ms)^(.)<[SSN>d{3}-?d{2}-?(d{4}.*)$" FORMAT = $1<SSN>###-##-$2
KEY = _raw
B . props.conf
[mask-SSN]
REGEX = (?ms)^(.)<[SSN>d{3}-?d{2}-?(d{4}.*)$"
FORMAT = $1<SSN>###-##-$2
DEST_KEY = _raw
C . transforms.conf [mask-SSN]
REX = (?ms)^(.)<[SSN>d{3}-?d{2}-?(d{4}.*)$" FORMAT = $1<SSN>###-##-$2 DEST_KEY = _raw
D . transforms.conf
[mask-SSN]
REGEX = (?ms)^(.)<[SSN>d{3}-?d{2}-?(d{4}.*)$"
FORMAT = $1<SSN>###-##-$2
DEST_KEY = _raw

Answer: D

Explanation:

because transforms.conf is the right configuration file to state the regex expression. https://docs.splunk.com/Documentation/Splunk/8.1.0/Admin/Transformsconf

Reference: https://community.splunk.com/t5/Archive/How-to-mask-SSN-into-our-logs-going-into-Splunk/tdp/433035