Final answer:
In psychoanalytic theory, the sexual intercourse in the dream likely symbolizes the latent content, which represents the unconscious wishes and desires behind the literal scenario of horseback riding. So, the correct answer is option a.
Step-by-step explanation:
In the context of psychoanalysis and dream interpretation, sexual intercourse in the question's scenario represents the latent content of the dream. The latent content refers to the hidden psychological meaning behind the manifest content, which is the dream's apparent and visible narrative. In this case, the act of horseback riding in the woman's dream might be analyzed by a psychoanalyst as a symbol of sexual desire, which is the latent content that underlies the manifest content of riding a horse.
So, the correct answer is option a.