Final answer:
The governess may believe Flora has seen an apparition based on her own psychological state, while Flora might try to challenge this belief by sternly denying it or offering rational explanations for any supposed sighting.
Step-by-step explanation:
The governess in the story may be convinced that Flora sees the apparition on the other side of the lake through a combination of circumstantial evidence and her own suspicions or psychological state. Flora could try to convince the governess she has not seen the apparition by firmly denying any sighting, offering rational explanations for any odd behavior, or by questioning the governess's own perceptions.
However, the success of convincing the governess may largely depend on the governess's willingness to believe Flora's explanations or her openness to alternative interpretations of the events.