Which of these is true?
A
Both veins and arteries carry oxygen-rich blood.
B
Both veins and arteries carry oxygen-poor blood.
C
Veins carry oxygen-poor blood, and arteries carry oxygen-rich blood.
D
Veins carry oxygen-rich blood, and arteries carry oxygen-poor blood.
C
Veins carry oxygen-poor blood, and arteries carry oxygen-rich blood.