An ophthalmologist used 1% mesaton (phenylephrine) solution for diagnostic purposes (dilation of pupils for examination of the fundus of the eye). In this case, drug-induced mydriasis is caused by:

Answer options

1. Blockade of alpha-1 adreno receptors
2. Activation of 2 adreno receptors
3. Activation of beta-1 adreno receptors
4. Activation of muscarinic acetylcholine receptors
5. Activation of alpha-1 adreno receptors