How would the current configuration impact the ability to achieve the desired result?

Ursa Major Solar has a lookup relationship between a custom Galaxy _c object and a custom Star_c object. An app builder wants to create a roll-up summary field that counts the total number of Star_c records related to each Galaxy__c record.

How would the current configuration impact the ability to achieve the desired result?
A . The roll-up summary can be achieved by creating a formula field on the Galaxy__c object.
B . The lookup relationship will need to be converted to a master-detail relationship before a roll-up summary field can be created.
C . The roll-up summary can be achieved by creating a formula field on the Star__c object.
D . A roll-up summary field will need to be created on the Galaxy__c object with a field filter that select all related Star_c records

Answer: B

Explanation:

The lookup relationship will need to be converted to a master-detail relationship before a roll-up summary field can be created. This is correct because roll-up summary fields are only available on the master object in a master-detail relationship, and a lookup relationship does not establish a parent-child hierarchy between the objects