Alead record that has a single related campaignmember object is converted into a new account, contact, and opportunity. which object will the campaignmember reference using a lookup field after conversion

When you convert officially recognized leads, Salesforce progress any campaign members to the new contacts. The leads become accessible but not modified records unless the administrator itself gives the consent to revise them. If the existing contacts and accounts are sharing the names particularized on the leads, it can be chosen to improve the existing accounts and contacts.