The Four Cs of 21st century learning, also known as the Four Cs or 4 Cs, are four skills that have been identified by the United States-based Partnership for 21st Century Skills (P21) as the most important skills required for 21st century education: critical thinking, communication, collaboration, and creativity.
Creativity and three other skills that start with C are required for 21st century education.
This statement is correct because I state that there are four skills that have been deemed to be required for 21st century education.  I think the system got confused because I was vague and didn't specify the skills.