Question

the human cardiovascular system is considered closed because ____________. a. blood is continuously circulated in the body. b. blood provides nutrients to organs. c. blood collects oxygen from the lungs d there are no holes for blood to enter or leave the system please select the best answer from the choices provided. o a o b o c o d

Explanation:

A closed system means there are no openings for substances to enter or leave. In the context of the human cardiovascular system, this implies no holes for blood to enter or leave. Option A describes circulation but doesn't directly address the 'closed' nature. Option B is about a function of blood (providing nutrients) not the system's closure. Option C is about gas exchange (oxygen collection) which is also a function, not related to the system being closed. Option D directly states there are no holes for blood to enter or leave, which is the definition of a closed system in this context.

Answer:

D. there are no holes for blood to enter or leave the system