Norepinephrine
(i) is released by sympathetic fibers
(ii) is released by parasympathetic fibers
(iii) increases the heart rate
(iv) decreases blood pressure.

Which of the above statements are correct?

(i) and (iii) are correct. (ii) and (iv) are incorrect.

(i) Sympathetic fibres release the neurotransmitter norepinephrine.

(ii) Parasympathetic fibres release acetylcholine.

(iii) Norepinephrine increases heart rate and cardiac output.

(iv) Acetylcholine released by parasympathetic fibres decreases blood pressure. 

(2) (ii) is incorrect.

(3) (ii) and (iv) are true about acetylcholine.

(4) (iv) is incorrect.