Use AWS Budgets to set custom budgets based on your costs, usage, reservation utilization, and reservation coverage.

=> Answer: B

(AWS Budgets: Create budget and send alarms when costs exceeds the budget)

Reference:

https://aws.amazon.com/blogs/security/guidelines-for-protecting-your-aws-account-while-using-programmatic-access/

A and C is correct...

Amazon S3 bucket permissions (free)

Checks buckets in Amazon Simple Storage Service (Amazon S3) that have open access permissions.

Bucket permissions that grant List access to everyone can result in higher than expected charges if objects in the bucket are listed by unintended users at a high frequency. Bucket permissions that grant Upload/Delete access to everyone create potential security vulnerabilities by allowing anyone to add, modify, or remove items in a bucket.

This check examines explicit bucket permissions and associated bucket policies that might override the bucket permissions.

Multi-factor authentication on root account (free)

Checks the root account and warns if multi-factor authentication (MFA) is not enabled.

For increased security, we recommend that you protect your account by using MFA, which requires a user to enter a unique authentication code from their MFA hardware or virtual device when interacting with the AWS console and associated websites.

It is C.

Q: What key management features are available in AWS KMS?

A: Define which IAM users and roles can use keys to encrypt and decrypt data

Reference: https://aws.amazon.com/kms/faqs/#:~:text=Q%3A%20What%20key%20management%20features,ever%20used%20within%20the%20service

Should be B&C.

AWS Trusted Advisor can improve the security of your application by closing gaps,

enabling various AWS security features,

and examining your permissions.

Reference:

https://aws.amazon.com/compliance/data-center/controls/

Answer is B.

The Performance Efficiency pillar includes the ability

to use computing resources efficiently to meet system requirements,

and to maintain that efficiency as demand changes and technologies evolve.

The Reliability pillar encompasses the ability of a workload to perform its intended function correctly

and consistently when it’s expected to.