Which statement describes why more than one collection would need to be created in IBM Watson Discovery service?

Which statement describes why more than one collection would need to be created in IBM Watson Discovery service?
A . It is better to have multiple small collections than one big collection
B . The first collection uses default configuration for testing and additional collections are needed for custom configurations
C . To keep similar file types in their respective collections
D . The data may be so different that it doesn’t make sense for it all to be queried at once

Answer: D

Explanation:

Reference: https://ibmcloud-watson-day.mybluemix.net/files/discovery_V3.1.pdf