Final answer:
According to Freud, the most important erogenous zone during earliest infancy is the mouth. In the oral stage of development, pleasure is focused on the mouth, eating, and sucking activities. This stage can influence oral fixations or tendencies in adulthood.
Step-by-step explanation:
According to Freud's psychosexual theory of development, the most important erogenous zone during earliest infancy is the mouth. In the oral stage of development (birth to 1 year), pleasure is focused on the mouth, eating, and sucking activities. This stage is characterized by the need for oral stimulation and the development of oral fixations or tendencies in adulthood, such as nail-biting or overeating.