Indicate whether each statement is correct or incorrect regarding pco2.

a. the closer the paco2 value is to the peco2 value, the lower the vd/vt is.
b. the higher the peco2 value is, the lower the vco2 is due to reduced alveolar ventilation
c. the paco2, paco2, and peco2 normally equilibrate in healthy subjects
d. the lower the paco2 is, the higher the pao2 is