Which of the Following Occurs During the Onset of Inspiration

Which of the following occurs during the onset of inspiration?

A) Intrathoracic pressure increases and venous return to the heart is impeded.
B) Intrathoracic pressure increases and venous return to the heart is facilitated.
C) Intrathoracic pressure decreases and venous return to the heart is impeded.
D) Intrathoracic pressure decreases and venous return to the heart is facilitated.