Duplicate management is a feature that allows administrators to prevent or allow duplicate records for standard or custom objects. Duplicate management consists of two components: duplicate rules and matching rules.

B) Configure custom duplicate rules.

Duplicate rules are rules that determine what actions to take when users try to save duplicate records. Duplicate rules can block users from saving duplicates, alert users of duplicates and let them save anyway, or report on duplicates without affecting the save operation. Duplicate rules can also specify which fields to use for matching and which security settings to enforce. By configuring custom duplicate rules, the sales team administrator can prevent duplicate records from being created for contacts or other objects. References: https://help.salesforce.com/s/articleView?id=sf.data_prevent_duplicates.htm &type=5

C) Create custom matching rules.

Matching rules are rules that determine how duplicate records are identified by comparing fields and applying fuzzy matching algorithms. Matching rules can be standard or custom. Standard matching rules are predefined by Salesforce and apply to common objects such as contacts, accounts, or leads. Custom matching rules are created by administrators and apply to any standard or custom object. By creating custom matching rules, the sales team administrator can define how duplicate records are detected for contacts or other objects. References: https://help.salesforce.com/s/articleView?id=sf.data_matching_rules.htm &type=5