The human immunodeficiency virus (HIV) destroys infection-fighting helper T-cells. The body system disrupted by HIV is the system. skeletal

respiratory

immune

excretory

ecological efficiency: % of usable energy transferred as

biomass from one trophic level to the next typical is 10% efficient (90% of

energy is lost),is diagramed as the pyramid of energy flow. then osprey eagle

are tertiary consumer and the shrimp are primary consumer, so to balance

mass of shrimp (1/0.1) / 0.1 = 100 kg 

the tricuspid valve is present between right atrium and right ventricle

the answer is definitely a