In ServiceNow Discovery, relationships between Configuration Items (CIs) in a horizontal pattern are created using the 'Create Relation/Reference' operation. This operation allows the pattern to define and establish relationships or references between discovered CIs, based on the information gathered during the discovery process. Options B and C are incorrect as relationships are not automatically created nor is it true that they cannot be created via patterns. Option D, 'Create Connections,' is not a standard operation in this context. Reference = ServiceNow Discovery documentation, specifically the sections on creating and managing horizontal discovery patterns.