This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: ANS, Subject name: Pharmacology
A child, Ramu has swallowed the contents of 2 bottles of a nasal decongestant whose primary ingredient is a adrenoceptor agonist drug. The signs of a activation that may occur in this patient include : 
Select and explain. 
A. Tachycardia, B. Dilatation of pupil, C. Vasodilation, D. All of the above
B: Dilatation of pupil
Answer: B: Dilatation of pupil 
Explanation: a-receptors are present on the radial muscles of the iris. Stimulation of a-receptors cause contraction of the radial muscles and will cause mydriasis Whereas tachycardia and vasodilation are due to activation of b-adrenergic receptors.