Surface with an intact toad on it was inclined to the right. Tone of extensor muscles became reflectory higher due to the activation of the following receptors:

Answer options

1. Proprioreceptors
2. Vestibuloreceptors of utricle and saccule
3. Photoreceptors of retina
4. Vestibuloreceptors of semicircular ducts
5. Mechanoreceptors of foot skin

Explanation

Vestibuloreceptors of utricle and saccule are responsible for the tone of extensor muscles in the toad.