A master-detail relationship can be converted to a look-up relationship if there are no roll-up summary fields existing on the master object.

Answer options:

A.True
B.False

Correct Answer: A 
If roll-up summary fields are not existing on a master object the master-detail relationship can be converted to a look-up relationship. 
Reference: 

https://help.salesforce.com/articleView?id=relationships_considerations.htm&type=5