What would produce maximum excitation of the hair cells in the right horizontal semicircular canal?

Rotating the head to the right

The semicircular canals are involved in angular acceleration or rotation. Hair cells of the right semicircular canal are excited (depolarized) when there is rotation to the right. This rotation causes bending of the tereocilia toward the kinocilia, and this bending produces depolarization of the hair cell. Ascent in an elevator would activate the saccules, which detect linear acceleration.