You have created a Lambda function for reading data from the Kinesis stream of transactions. In the code, you were using a context logger to log to CloudWatch, and you can monitor them at a later point of time. Lambda function started running along with Kinesis stream. However, you do not see any log entries for the new Lambda function. What could be the reason?

Answer options:

A.Lambda functions with Kinesis stream as event source do not write logs to CloudWatch.
B.Lambda execution role policy does not have access to create CloudWatch logs.
C.Lambda function execution logs will be written to CloudTrail, not to CloudWatch.
D.Active tracing is not enabled on the Lambda function setup configuration.

Answer: B
Option A is not a valid statement. Lambda function will write logs as long as the execution role has access to create and write CloudWatch logs irrespective of the source that triggered it.
Option B is correct.
Option C is not correct. AWS CloudTrail is used for logging API calls made to services such as AWS Lambda, AWS S3 etc.
AWS CloudWatch for Lambda is used for execution logging. 
https://docs.aws.amazon.com/lambda/latest/dg/with-cloudtrail.html
Option D is not correct. AWS X-Ray traces requests made to your serverless applications built using AWS Lambda. This will not be the reason for failing to write logs to CloudWatch.
https://docs.aws.amazon.com/lambda/latest/dg/lambda-x-ray.html