For which objects are the contact roles available for both Salesforce classic and lightning?

Answer options:

A.Leads
B.Opportunities
C.Contracts
D.Solutions

Correct Answer: B and C 
In Salesforce classic, contact roles are available for the account, opportunities, case, and contracts but for Salesforce lightning contact roles are available for opportunities and contracts. 
Options A and D are incorrect because contact roles are not available for leads and solutions in both Salesforce classic and lightning. 
Reference: 

https://help.salesforce.com/articleView?id=contactroles.htm&type=5