Explanation
To ensure that key fields are populated when creating leads manually, the consultant should apply the following functionalities:
A required field. This forces the user to enter a value for a field before saving a record. The administrator can make a field required at the page layout level or at the field definition level.
A validation rule. This checks that the data entered by a user meets certain standards before saving a record. The administrator can create a validation rule with a formula that evaluates whether a field meets certain criteria, such as length, format, or value.