Question

required information
when the pressure in the ventricles becomes lower than the pressure in the atria, _.
multiple choice
the ventricles contract
blood flows into the pulmonary trunk
blood flows into the aorta
the atrioventricular valves open
the semilunar valves open

Explanation:

When ventricular pressure is lower than atrial pressure, the atrioventricular (AV) valves open. This allows blood to flow from the atria into the ventricles. Ventricular contraction (first option) would increase ventricular pressure. Blood flowing into the pulmonary trunk (second option) and aorta (third option) occurs when semilunar valves open, which is when ventricular pressure exceeds arterial pressure. Semilunar valves (fifth option) open when ventricular pressure is higher than arterial pressure, not when ventricular pressure is lower than atrial pressure.

Answer:

the atrioventricular valves open