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 lookup relationship will need to be converted to a master-detail relationship before a roll-up summary field can be created.
B. A roll-up summary field will need to be created on the Galaxy＿ c object with a field filter that selects all related Star＿c records.
C. The roll-up summary can be achieved by creating a formula field on the Galaxy＿c object.
D. The roll-up summary can be achieved by creating a formula field on the Star＿c object.

Suggest answer: A

Reference: