What is a common cause of the NPSP upgrade failing when run in Production and there were no issues running it in the sandbox?

What is a common cause of the NPSP upgrade failing when run in Production and there were no issues running it in the sandbox?
A . Not having adequate test code coverage
B . Not having one or more of the packages in NPSP installed
C . Not running the NPSP Health Check before trying to upgrade in production
D . Not changing the account model to the Household Account Model before trying to upgrade

View Answer

Answer: A