In a positive feedback loop, how are the response and original stimulus-related?

A. The response does not affect the original stimulus.
B. The response counteracts the original stimulus.
C. The response stops the original stimulus.
D. The response amplifies the original stimulus.

B. The response counteracts the original stimulus.

Maybe I dont know

there is no

explanation:

blood enters the heart through two large veins, the inferior and superior vena cava, emptying oxygen-poor blood from the body into the right atrium of the heart. as the ventricle contracts, blood leaves the heart through the pulmonic valve, into the pulmonary artery and to the lungs where it is oxygenated.