Assertion [A]: In the field of healthcare, both the private and the cooperative sector are important.
Reason [R]: The private and cooperative sector operate various multispecialty hospitals.

The correct option is C A and R are true and R is the correct explanation of A.
In the field of healthcare, the private sector and the cooperative sector are important. The private and cooperative sectors operate various multispeciality hospitals in the cities, which specialise in treating different types of diseases and usually have all kinds of modern facilities available for patients. These facilities for the public's welfare would have been absent on a large scale without the private and cooperative sector, helping the public/government sector in the healthcare domain.