The potential energy level diagrams for two molecules $($A & B$)$ in the ground and excited state are shown below. Based on these diagrams, answer the following questions:

$($i$)$ Write a note explaining why the line indicating the transition from the ground state to the excited state is vertical.

$($ii$)$ Based on the energy level diagrams for molecules A & B$,$ comment on the extent of molecular distortion associated with each molecule when in an excited state.

$($iii$)$ In terms of the intensity of the observed transitions, indicate the most intense transition that would be expected for molecule A & B$.$