Final answer:
The first three psychosexual stages, according to Sigmund Freud, are the oral stage, a.n.a.l stage, and phallic stage.
Step-by-step explanation:
Freud proposed that children pass through distinct psychosexual stages: the oral stage (birth to 18 months) where pleasure centers on the mouth, the a.n.a.l stage (18 months to 3 years) focused on toilet training and control, and the phallic stage (3 to 6 years) marked by the Oedipus or Electra complex where children become aware of their bodies and develop attachments to the opposite-sex parent.
In the oral stage, infants explore the world through their mouths, finding pleasure in sucking and tasting. During the a.n.a.l stage, a child's focus shifts to bowel and bladder control, influencing aspects of personality development related to orderliness and messiness. The phallic stage introduces the awareness of gender differences and a child's identification with their same-sex parent. These stages lay the groundwork for later personality development.
The correct answer, in order of occurrence, is the oral stage, a.n.a.l stage, and phallic stage according to Freudian theory.