Answer: C.
Option A is INCORRECT because in order to feed a Data Streams from custom logs you have to change the application code.
AWS documentation describes this with the following sentence: “To put data into the stream, you must specify the name of the stream, a partition key, and the data blob to be added to the stream.”
Option B is INCORRECT because it is not related to the scenario and custom log files.
Option C is CORRECT because AWS CloudWatch Logs has the capability to reuse existing application logs increasing efficiency in operation with the ability to generate on them metrics, alerts and analytics with AWS CloudWatch Logs Insight.