Which of the following statements correctly describes the relationship between respiratory rate, intrathoracic pressure, and the filling of the heart?
a) Increase in respiratory rate decreases intrathoracic pressure, facilitating heart filling
b) Increase in respiratory rate increases intrathoracic pressure, facilitating heart filling
c) Decrease in respiratory rate decreases intrathoracic pressure, hindering heart filling
d) Decrease in respiratory rate increases intrathoracic pressure, hindering heart filling