Your organization has two accounts, for DEV and TEST. You have certain user applications running on the TEST account would like to trigger AWS Lambda on the DEV account. What is the permission model which needs to be set to get this configuration working?

Answer options:

A.Add permission for TEST account on DEV account’s lambda function policy through AWS CLI.
B.Add permission for TEST account on DEV account’s lambda execution role policy through AWS Console.
C.Add permission for TEST account on DEV account’s lambda execution role policy through AWS CLI.
D.Add permission for TEST account on DEV account’s lambda function policy through AWS Console.

Answer: A
https://docs.aws.amazon.com/lambda/latest/dg/access-control-resource-based.html?shortFooter=true#access-control-resource-based-example-cross-account-scenario
Options B, C are not correct. Permission needs to be added to the Lambda function policy to invoke the function, not on the execution role policy.
Option D is not correct. Lambda function policy cannot be edited from the AWS console.
For more information, please fere to the below mentioned AWS docs:
https://docs.aws.amazon.com/lambda/latest/dg/access-control-resource-based.html