Which of the following are the features for unmanaged packages? Choose three

Answer options:

A.To receive an upgrade, you must uninstall the package from your org and then reinstall a new version from AppExchange.
B.The contents of the package count against the app, tab, and object limits in your org.
C.The provider can automatically upgrade the offering.
D.You can customize code and metadata, if desired.

Correct Answer: A, B, and D 
Unmanaged Packages content counts against the app, tab and object limits in your org and you can customize the code and metadata if needed but receiving an upgrade will require removing the package and installing the new version again. 
Option C is incorrect because the provider cannot automatically upgrade the offering. This a feature for managed packages. 
Reference: 

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