In which of the following conditions would ventricular pressure increase?

Ventricular pressure increases when the ventricles contract because this is the phase of the cardiac cycle known as ventricular systole. During this phase, the heart muscle contracts and the volume within the ventricles decreases as blood is ejected into the arteries. As the muscle contracts, the pressure within the ventricles rises significantly. This increase in pressure is essential for propelling blood into the systemic and pulmonary circulations through the aorta and pulmonary artery, respectively.

In contrast, during diastolic phases or isovolumetric relaxation, the pressures would not be increasing in the ventricles. During atrial systole, while the atrial pressure may rise as they contract, this action does not contribute to an increase in ventricular pressure until the ventricles receive blood from the atria, which occurs just before the ventricles contract.