Which statement retrieves an item from the MusicCollection table in DynamoDB?
a. aws dynamodb query --table-name MusicCollection --key file://key.json
b. aws dynamodb get-item --table-name MusicCollection --key file://key.json
c. aws dynamodb select --table-name MusicCollection --key file://key.json
d. aws dynamodb put-item --table-name MusicCollection --key file://key.json