A company is planning on using a plethora of AWS services such as AWS RDS and Amazon Redshift. They need to have a unified metadata repository for all of these data sources. Which of the following is the ideal service to use for this purpose?

Answer options:

A.AWS Athena
B.AWS Glue
C.AWS EMR
D.AWS Quick Sight

Answer – B
The AWS Documentation mentions the following
AWS Glue is a fully managed extract, transform, and load (ETL) service that makes it simple and cost-effective to categorize your data, clean it, enrich it, and move it reliably between various data stores. The AWS Glue Data Catalog provides a unified metadata repository across a variety of data sources and data formats, integrating with Amazon EMR as well as Amazon RDS, Amazon Redshift, Redshift Spectrum, Athena, and any application compatible with the Apache Hive metastore. AWS Glue crawlers can automatically infer schema from source data in Amazon S3 and store the associated metadata in the Data Catalog. 
All other options are incorrect because these cannot be used to catalog the information
For more information on EMR Spark Glue, please refer to the below URL
https://docs.aws.amazon.com/emr/latest/ReleaseGuide/emr-spark-glue.html