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