AWS Cost Explorer
Cost Explorer is a tool to visualize and analyze past costs that have already been incurred.
It is not a tool for estimating a configuration you have yet to build, so it is incorrect.
For an AWS configuration you plan to build, you want to estimate the approximate monthly cost in advance before you actually build it. Which tool is best?
Choosing the pre-build cost estimation tool.
AWS Cost Explorer
Cost Explorer is a tool to visualize and analyze past costs that have already been incurred.
It is not a tool for estimating a configuration you have yet to build, so it is incorrect.
AWS Pricing Calculator
Correct. AWS Pricing Calculator lets you enter the configuration you plan to build (instance types, counts, storage size, and so on) and estimate the approximate monthly cost in advance before you actually build it. It is useful for proposals and budgeting.
AWS CloudTrail
CloudTrail is an audit service that records the history of API operations.
It is not a tool for estimating cost in advance, so it is incorrect.
Amazon CloudWatch
CloudWatch is a service that monitors resource metrics.
It is not a tool for estimating cost in advance, so it is incorrect.
'Before building' and 'estimate cost' point to AWS Pricing Calculator. 'Analyze past cost' is Cost Explorer. Distinguish up-front (Calculator) from actuals (Cost Explorer).