For data from a custom Lead field to be transferred to a Contact during lead conversion, a corresponding custom field must first exist on the Contact object. The data types must be compatible; in this case, a custom picklist on the Lead requires a custom picklist on the Contact. After creating the destination field on the Contact object, the administrator must then explicitly map the source Lead field to the new Contact field. This mapping instructs Salesforce to transfer the value during the conversion process. Both steps are essential for the data to populate correctly.

A. A validation rule is used to enforce data quality and integrity before a record is saved; it does not facilitate data transfer between objects.

D. Making a field required on the Lead ensures it contains a value, but this action does not configure the system to transfer that value to another object.

1. Salesforce Help, "Map Custom Lead Fields for Lead Conversion": This document states, "You can map custom lead fields to custom fields in accounts, contacts, and opportunities... For each custom lead field, choose a custom account, contact, or opportunity field into which you want the information inserted when you convert a lead." This confirms that a destination field must exist (Step B) and that mapping is required (Step C).

2. Salesforce Help, "Considerations for Converting Leads": Under the "Mapping Custom Lead Fields" section, the documentation clarifies, "When you map a custom lead field, that field isn’t created on the account, contact, or opportunity. Before you map custom lead fields, create the custom field on the account, contact, or opportunity." This explicitly details the necessity of first creating the field (Step B) before mapping it (Step C).

3. Trailhead, Salesforce Platform Basics, "Data Modeling" Module, "Work with Schema Builder" Unit: This module explains the fundamental principle that objects must have defined fields to store data. To store the lead's picklist value on a contact, the Contact object must first be customized to include a field of a compatible type.