Which statement below best describes the relationship between SARS-CoV-2, coronavirus, and COVID-19?

a) two types of coronavirus are SARS-CoV-2 and COVID-19
b) COVID-19 causes the coronavirus while SARS-CoV-2 causes COVID-19
c) SARS-CoV-2 is a type of coronavirus that causes the disease COVID-19
d) COVID-19 is a disease caused by both the coronavirus and SARS-CoV-2