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