Practical medical instruments and equipment refer to

A. Instruments, equipment, appliances, materials or other articles directly or indirectly used in human body, including required software;

B. Instruments, equipment, appliances, materials or other articles directly acting on human body, including required software;

C refers to instruments, equipment, appliances, materials or other articles directly or indirectly used in human body, except intangible software;

D. Instruments, equipment, appliances and materials directly or indirectly used in human body, including required software;

Correct answer: a